TECHNICAL FIELD
[0001] The present disclosure generally relates to gas turbine engines, and more particularly
relates to compact accessory systems for a gas turbine engine, such as a compact accessory
gearbox for use with a gas turbine engine.
BACKGROUND
[0002] Gas turbine engines may be employed to power various devices. For example, a gas
turbine engine may be employed to power a mobile platform, such as an aircraft. Typically,
gas turbine engines include accessories that assist in engine operation and in the
operation of the mobile platform, which are driven by the gas turbine engine. The
accessories are generally positioned within an engine nacelle. The arrangement of
the accessories in the engine nacelle influences the size of the engine nacelle, which
may increase drag on the mobile platform.
[0003] Patent document number
FR3006733A1 describes a drive housing for an engine comprising a drive shaft, in particular a
turboprop, adapted to drive at least two accessories each comprising a drive shaft.
The accessory drive housing comprises: a primary shaft; a primary angle gear, comprising
a gear driven by the drive shaft; and a primary engaging member, fixed to the primary
shaft driving the primary shaft for each attachment. Each drive assembly is driven
by the primary shaft.
[0004] Patent document number
FR3017660A1 describes an auxiliary machine drive assembly for driving auxiliary machines in an
aircraft turbojet. The auxiliary machine drive assembly reduces the bulkiness of the
accessory gearbox (AGB) and auxiliary machinery. The auxiliary machine drive assembly
comprises an accessory gearbox comprising a housing on which first attachments can
be attached. The main drive shaft is adapted to be rotated relative to the housing
through a radial drive shaft of a turbomachine and a drive shaft. The assembly further
comprises a plurality of bevel gears mounted integrally with the main drive shaft,
each conical pinion being adapted to cooperate with a conical pinion of one of the
first equipment to drive a rotor of the first equipment. The assembly further comprises
a stator and a rotor, the stator being mounted integral with the housing and the rotor
being mounted integral with the main drive shaft.
[0005] Patent document number
WO2014/130239A2 describes a lubrication pump which includes a main pump stage, an auxiliary pump
stage, and scavenger pump stages. The lubrication pump is driven by a common shaft
of the accessory gearbox.
[0006] Patent document number
US2015/308350A1 describes multi-axis accessory gearboxes of mechanical drive systems and gas turbine
engines.
[0007] Accordingly, it is desirable to provide compact accessory systems for a gas turbine
engine, which includes a compact accessory gearbox having a reduced size that enables
a reduction in a volume of an engine nacelle. Furthermore, other desirable features
and characteristics of the present invention will become apparent from the subsequent
detailed description and the appended claims, taken in conjunction with the accompanying
drawings and the foregoing technical field and background.
SUMMARY
[0008] The present invention in its various aspects is as set out in the appended claims.
[0009] In various embodiments, provided is an accessory system for a gas turbine engine
having a driveshaft with an axis of rotation. The accessory system includes a towershaft
coupled to the driveshaft and driven by the driveshaft along a towershaft axis of
rotation transverse to the axis of rotation of the gas turbine engine. The towershaft
includes a towershaft bevel gear at a distal end. The accessory system also includes
a shaft including a first shaft bevel gear coupled to the towershaft bevel gear. The
shaft is rotatable by the towershaft along a shaft axis of rotation. The shaft axis
of rotation is transverse to the towershaft axis of rotation and substantially parallel
to the axis of rotation of the gas turbine engine. The accessory system includes a
first accessory drive shaft having a first accessory bevel gear driven by the shaft,
and the first accessory drive shaft has a first accessory axis of rotation. The accessory
system also includes a second accessory drive shaft having a second accessory bevel
gear driven by the shaft. The second accessory drive shaft has a second accessory
axis of rotation, and each of the first accessory axis of rotation and the second
accessory axis of rotation are substantially transverse to the shaft axis of rotation.
The secondary accessory axis of rotation and the first accessory axis of rotation
are substantially transverse to each other.
[0010] Also provided according to various embodiment is an accessory system for a gas turbine
engine having a driveshaft with an axis of rotation. The accessory system includes
a towershaft coupled to the driveshaft and driven by the driveshaft along a towershaft
axis of rotation transverse to the axis of rotation of the gas turbine engine. The
towershaft includes a towershaft bevel gear at a distal end. The accessory system
comprises a shaft including a first shaft bevel gear coupled to the towershaft bevel
gear, and the shaft is rotatable by the towershaft along a shaft axis of rotation.
The shaft axis of rotation is transverse to the towershaft axis of rotation and substantially
parallel to the axis of rotation of the gas turbine engine. The shaft includes a second
shaft bevel gear spaced apart from a third shaft bevel gear by a spacer. The accessory
system also includes a first accessory drive shaft having a first accessory bevel
gear coupled to the second shaft bevel gear, and the first accessory drive shaft has
a first accessory axis of rotation. The accessory system includes a second accessory
drive shaft having a second accessory bevel gear coupled to the third shaft bevel
gear. The second accessory drive shaft has a second accessory axis of rotation, and
each of the first accessory axis of rotation and the second accessory axis of rotation
are substantially transverse to the shaft axis of rotation. The secondary accessory
axis of rotation and the first accessory axis of rotation are substantially transverse
to each other.
[0011] Further provided according to various embodiments is an accessory system for a gas
turbine engine having a driveshaft with an axis of rotation. The accessory system
includes a towershaft coupled to the driveshaft and driven by the driveshaft along
a towershaft axis of rotation transverse to the axis of rotation of the gas turbine
engine. The towershaft includes a towershaft bevel gear at a distal end. The accessory
system includes a shaft including a first shaft bevel gear coupled to the towershaft
bevel gear. The shaft is rotatable by the towershaft along a shaft axis of rotation,
and the shaft axis of rotation is transverse to the towershaft axis of rotation and
substantially parallel to the axis of rotation of the gas turbine engine. The accessory
system also includes a first accessory drive shaft having a first accessory bevel
gear driven by the shaft, and the first accessory drive shaft has a first accessory
axis of rotation. The accessory system includes a second accessory drive shaft having
a second accessory bevel gear driven by the shaft. The second accessory drive shaft
has a second accessory axis of rotation, and each of the first accessory axis of rotation
and the second accessory axis of rotation are substantially transverse to the shaft
axis of rotation. The secondary accessory axis of rotation and the first accessory
axis of rotation are substantially transverse to each other, and the first accessory
axis of rotation intersects the shaft axis of rotation at a first point and the second
accessory axis of rotation intersects the shaft axis of rotation at a second point.
The accessory system includes a third accessory drive shaft having a third accessory
bevel gear driven by the shaft. The third accessory drive shaft has a third accessory
axis of rotation, and the third accessory axis of rotation intersects the shaft axis
of rotation at a third point, with the second point different than the first point
and the third point.
DESCRIPTION OF THE DRAWINGS
[0012] The exemplary embodiments will hereinafter be described in conjunction with the following
drawing figures, wherein like numerals denote like elements, and wherein:
Fig. 1 is a schematic cross-sectional illustration of a gas turbine engine, which
includes an exemplary compact accessory system including an exemplary compact accessory
gearbox in accordance with the various teachings of the present disclosure;
Fig. 1B is a schematic cross-sectional illustration of a gas turbine engine, which
includes an exemplary compact accessory system including an exemplary compact accessory
gearbox in accordance with the various teachings of the present disclosure;
Fig. 2 is a top view of the compact accessory system of Fig. 1;
Fig. 3 is a bottom view of the compact accessory system of Fig. 1, with a portion
of the compact accessory gearbox removed;
Fig. 4 is a front view of an exemplary adaptor for use with the compact accessory
system of Fig. 1;
Fig. 5 is a cross-sectional view of the adaptor of Fig. 4, taken along line 5-5 of
Fig. 4;
Fig. 6 is an exploded perspective view of an exemplary bearing assembly for use with
the compact accessory system of Fig. 1;
Fig. 7 is an exploded perspective view of the adaptor of Fig. 4;
Fig. 8 is a top view of the compact accessory gearbox of Fig. 1;
Fig. 9 is a back view of the compact accessory gearbox of Fig. 1;
Fig. 10 is a bottom view of a gear train of the compact accessory gearbox of Fig.
1;
Fig. 10A is a schematic perspective illustration of the gear train of Fig. 10, which
illustrates that a portion of the gear train is on an imaginary cone;
Fig. 10B is a schematic perspective illustration of the gear train of Fig. 10, which
illustrates that a portion of the gear train is on an imaginary cone;
Fig. 11 is an exploded perspective view of a shaft for use with the gear train of
Fig. 10 and the compact accessory gearbox of Fig. 1;
Fig. 12 is a cross-sectional view of the compact accessory gearbox of Fig. 8, taken
along line 12-12 of Fig. 8;
Fig. 13 is a perspective view of an exemplary oil tank for use with the compact accessory
gearbox of Fig. 1;
Fig. 14 is a schematic bottom view of a compact accessory gearbox for use with the
compact accessory system of Fig. 1 according to the various teachings of the present
disclosure;
Fig. 15 is a top view of a compact accessory system for use with the gas turbine engine
of Fig. 1, which includes a compact accessory gearbox in accordance with the various
teachings of the present disclosure;
Fig. 16 is a top view of a gear train for use with the compact accessory gearbox of
Fig. 15;
Fig. 17 is a cross-sectional view of the gear train of Fig. 16, taken along line 17-17
of Fig. 16;
Fig. 18 is a top view of a gear train for use with the compact accessory gearbox of
Fig. 15 in accordance with the various teachings of the present disclosure; and
Fig. 19 is a cross-sectional view of the gear train of Fig. 18, taken along line 19-19
of Fig. 18.
DETAILED DESCRIPTION
[0013] The following detailed description is merely exemplary in nature and is not intended
to limit the application and uses. Furthermore, there is no intention to be bound
by any expressed or implied theory presented in the preceding technical field, background,
brief summary or the following detailed description. In addition, those skilled in
the art will appreciate that embodiments of the present disclosure may be practiced
in conjunction with any type of gearbox that would benefit from a reduced or compact
configuration, and that the accessory systems and methods described herein for use
with a gas turbine engine is merely one exemplary embodiment according to the present
disclosure. Moreover, while the accessory systems and methods are described herein
as being used with a gas turbine engine onboard a mobile platform, such as a bus,
motorcycle, train, motor vehicle, marine vessel, aircraft, rotorcraft and the like,
the various teachings of the present disclosure can be used with a gas turbine engine
on a stationary platform. Further, it should be noted that many alternative or additional
functional relationships or physical connections may be present in an embodiment of
the present disclosure. In addition, while the figures shown herein depict an example
with certain arrangements of elements, additional intervening elements, devices, features,
or components may be present in an actual embodiment. It should also be understood
that the drawings are merely illustrative and may not be drawn to scale.
[0014] With reference to Fig. 1, a cross-sectional view of an exemplary gas turbine engine
10 is shown, which includes a compact accessory system 12 according to various embodiments.
It should be noted that while the compact accessory system 12 is discussed herein
with regard to the gas turbine engine 10, the compact accessory system 12 can be employed
with any suitable engine, such as a turbojet engine, an auxiliary power unit (APU),
etc. Thus, the following description is merely one exemplary use of the compact accessory
system 12. Moreover, while the gas turbine engine 10 is described herein as being
used with a mobile platform, such as an aircraft 8, it will be understood that the
gas turbine engine 10 may be used with any suitable platform, whether mobile or stationary.
[0015] In this example, the gas turbine engine 10 includes a fan section 14, a compressor
section 16, a combustor section 18, a turbine section 20, and an exhaust section 22.
The fan section 14 includes a fan 24 mounted on a rotor 26 that draws air into the
gas turbine engine 10 and accelerates it. A fraction of the accelerated air exhausted
from the fan 24 is directed through an outer (or first) bypass duct 28 and the remaining
fraction of air exhausted from the fan 24 is directed into the compressor 32.
[0016] In the embodiment of Fig. 1, the compressor section 16 includes a compressor 32.
However, in other embodiments, the number of compressors in the compressor section
16 may vary. In the depicted embodiment, the compressor 32 raises the pressure of
the air and directs the high pressure air into the combustor 36. A fraction of the
air bypasses the combustor 36 and enters a second bypass duct 34.
[0017] In the embodiment of Fig. 1, in the combustor section 18, which includes an annular
combustor 36, the high pressure air is mixed with fuel and combusted. The high-temperature
combusted air is then directed into the turbine section 20. The turbine section 20
includes three turbines disposed in axial flow series, namely, a high pressure turbine
38 and a low pressure turbine 42. However, it will be appreciated that the number
of turbines, and/or the configurations thereof, may vary. In this embodiment, the
high-temperature combusted air from the combustor section 18 expands through and rotates
each turbine 38 and 42. The air is then exhausted through a propulsion nozzle 44 disposed
in the exhaust section 22. As the turbines 38 and 42 rotate, each drives equipment
in the gas turbine engine 10 via concentrically disposed shafts or spools. In one
example, the high pressure turbine 38 drives the compressor 32 via a high pressure
driveshaft 46 and the low pressure turbine 42 drives the fan 24 via a low pressure
driveshaft 50. Generally, the high pressure driveshaft 46 and the low pressure driveshaft
50 are coaxially arranged along a longitudinal axis L of the gas turbine engine 10,
and each of the high pressure driveshaft 46 and the low pressure driveshaft 50 have
an axis of rotation R, which extends substantially parallel to and along the longitudinal
axis L.
[0018] In the example of Fig. 1, the high pressure driveshaft 46 includes a gear 52. In
this example, the gear 52 is a bevel gear, having a plurality of bevel gear teeth.
The gear 52 is coupled to a towershaft 54 and drives the towershaft 54. In one example,
the towershaft 54 includes a first end 54a and a second end 54b. The first end 54a
includes a gear 56, which in this example, comprises a bevel gear. The gear 56 includes
a plurality of bevel gear teeth, which are meshingly coupled to or engaged with the
plurality of bevel gear teeth of the gear 52. The engagement of gear 56 with gear
52 transfers torque from the high pressure driveshaft 46 to the towershaft 54, and
thus, drives or rotates the towershaft 54. The towershaft 54 is generally coupled
to the gear 52 such that the towershaft 54 extends along an axis of rotation Tr, which
is substantially transverse to the axis of rotation R of the high pressure driveshaft
46. One or more bearings or supports may be coupled to the towershaft 54 at or near
the first end 54a to support the towershaft 54 for rotation with the gear 56.
[0019] The second end 54b of the towershaft 54 is coupled to the compact accessory system
12 and forms part of the compact accessory system 12. In one example, the second end
54b of the towershaft 54 includes a sleeve 55. The sleeve 55 is coupled about the
second end 54b via splined coupling, for example, although any suitable joining technique
may be employed such that the sleeve 55 rotates in unison with the towershaft 54.
The sleeve 55 may be supported for rotation by a bearing 57, which is disposed in
a housing 59. The housing 59 couples the second end 55b of the sleeve 55 to the compact
accessory gearbox 60 and the bearing 57 supports the sleeve 55 for rotation relative
to a compact accessory gearbox 60. The sleeve 55 further includes a gear 58, such
as a bevel gear. The gear 58 is disposed at a second end 55b of the sleeve 55, and
includes a plurality of bevel gear teeth 58a. The plurality of bevel gear teeth 58a
are coupled about a perimeter or circumference of the gear 58. The gear 58 is coupled
to the compact accessory system 12, and the plurality of bevel gear teeth 58a meshingly
engage a bevel gear contained within the compact accessory gearbox 60 as will be discussed
further herein. Generally, the gear 58 transfers torque from the sleeve 55 and the
towershaft 54 to the compact accessory gearbox 60 to drive various components of the
compact accessory system 12. However, during an engine startup, power is delivered
from a starter turbine 64 (with air supplied by a starter valve 62) and into compact
accessory gearbox 60 at the correct speed (in revolutions per minute (rpm)), driving
the sleeve 55 and the towershaft 54, which drives the high pressure driveshaft 46
and turns the compressor 32 and high pressure turbine 38 of the gas turbine engine
10 allowing the gas turbine engine 10 to start. The compact accessory system 12, in
turn, drives various accessories associated with the gas turbine engine 10. In one
example, the compact accessory system 12 is mounted within a nacelle N of the gas
turbine engine 10.
[0020] With reference to Fig. 2, the compact accessory system 12 is shown in greater detail.
In this example, the compact accessory system 12 includes the compact accessory gearbox
60, which drives various accessories, including, but not limited to, a starter turbine
64, a direct-current (DC) generator 66, a hydraulic pump 68, a permanent magnet alternator
70, a fuel control unit 72, a lubrication pump 74 and an air-oil separator 76 (Fig.
3). The starter valve 62 supplies air to the starter turbine 64. Generally, the compact
accessory gearbox 60 is coupled to the towershaft 54 via the gear 58 to receive the
torque from the towershaft 54 and to drive the accessories 62-76. It should be noted
that the accessories 62-76 described herein are merely exemplary, as the compact accessory
gearbox 60 may be used to drive any suitable accessory associated with the gas turbine
engine 10. With brief reference to Figs. 4-6, the accessories 64-74 can be coupled
to the compact accessory gearbox 60 via an adaptor 80.
[0021] With reference to Figs. 4 and 5, the adaptor 80 includes an accessory interface 82
and a gearbox interface 84 (Fig. 5), which are interconnected via a central bore 85.
The adaptor 80 is composed of any suitable material, and in one example, is composed
of a metal or metal alloy. The adaptor 80 may be formed via casting, stamping, machining,
etc. The accessory interface 82 is generally opposite the gearbox interface 84 (Fig.
5). The accessory interface 82 is generally circular, however, the accessory interface
82 may have any desired shape to couple the respective accessory 64-74 to the compact
accessory gearbox 60.
[0022] In one example, the accessory interface 82 includes a first plurality of mounting
bores 86. The first plurality of mounting bores 86 are spaced apart along a perimeter
or circumference of the accessory interface 82. In one example, the mounting bores
86 comprise mounting slots, which are elongated about the circumference of the accessory
interface 82. In this example, two mounting fasteners (not shown) may be received
in each of the mounting bores 86, with one of the mounting fasteners received in a
first end 86a of the mounting bore 86, and another of the mounting fasteners received
in a second end 86b of the mounting bore 86. While not illustrated herein for clarity,
the mounting fasteners comprise any suitable coupling device for coupling the accessory
62-74 to the adaptor 80, including, but not limited to, a mechanical fastener assembly
including a threaded shank that engages a nut disposed about a surface 86c of the
mounting bores 86, etc. In addition, one of the mounting bores 86' may have a arcuate
length about the perimeter of the accessory interface 82 that is different than a
arcuate length of a reminder of the mounting bores 86". In this example, the arcuate
length of the mounting bore 86' is less than the arcuate length of the mounting bores
86" to aid in the alignment of the respective accessory 64-72 to the adaptor 80. Generally,
with reference to Fig. 5, the mounting bores 86 extend through an outer surface of
the accessory interface 82 and terminate at a base 88 of the accessory interface 82.
A v-band flange 88a may also be coupled to the adaptor 80, which may engage a corresponding
v-band flange associated with one or more of the accessories 64-72. The v-band flange
88a allows the accessory 64-72 with the corresponding or opposing v-band flange to
be connected to the adaptor 80 using a v-band clamp.
[0023] In addition, with reference to Fig. 4, the accessory interface 82 may include a piloting
bore 87. The piloting bore 87 may receive a piloting screw or other device to assist
in locating the respective accessory 64-72 on the accessory interface 82. The piloting
bore 87 generally terminates at the base 88, as illustrated in Fig. 6. With continued
reference to Fig. 6, the accessory interface 82 also includes a projection 89, which
adds material for a breather port defined through the adaptor 80. The projection 89
is coupled to the base 88 of the accessory interface 82, so as to be on a side of
the base 88 substantially opposite the mounting bores 86.
[0024] With reference to Figs. 5 and 6, the gearbox interface 84 couples the compact accessory
gearbox 60 to the adaptor 80. The gearbox interface 84 is generally circular, and
has a diameter, which is different than a diameter of the accessory interface 82.
The diameter of the gearbox interface 84 is generally smaller than the accessory interface
82. The gearbox interface 84 includes a second plurality of mounting bores 90, which
pass through the gearbox interface 84 and terminate along a surface 91a of a counterbore
91 defined through the accessory interface 82. The mounting bores 90 are generally
cylindrical, but the mounting bores 90 may have any desired shape. The mounting bores
90 are generally spaced apart about a perimeter or circumference of the gearbox interface
84. In one example, one of the mounting bores 90' is spaced a greater distance apart
from a reminder of the plurality of mounting bores 90" to aid in the assembly, clocking
and coupling of the adaptor 80 to the compact accessory gearbox 60; however, the mounting
bores 90 may be evenly spaced. In this example, the gearbox interface 84 defines three
mounting bores 90; however, the gearbox interface 84 may include any number of mounting
bores 90. The mounting bores 90 each receive a suitable mechanical fastener, such
as a bolt, etc., which tightens against a nut or nutplate received on the surface
92a, for example, to couple the adaptor 80 to the compact accessory gearbox 60.
[0025] With reference to Fig. 5, the central bore 85 is defined about a central axis CL
of the adaptor 80. In this example, the central bore 85 is sized to receive a bearing
assembly 93, which includes a first bearing 92, a spacer 94, a second bearing 96 and
a retaining ring 98. The central bore 85 includes a lip 100 at a first end 85a, which
serves to retain the first bearing 92 within the central bore 85. The central bore
85 also defines a recess 102 at a second end 85b, which receives the retaining ring
98 to retain the bearing assembly 93 within the central bore 85. Generally, the bearing
assembly 93 enables a respective shaft of the compact accessory gearbox 60 to rotate
within the adaptor 80 to drive the respective accessory 64-72. The first bearing 92
and the second bearing 96 each generally comprise a ball bearing, roller bearing,
duplex, air, or any other type of bearing, as known to one of skill in the art. The
spacer 94 comprises any suitable spacer, and in one example, comprises a metal ring
that is received between the first bearing 92 and the second bearing 96. The retaining
ring 98 comprises a metal retaining ring, which is elastically deformable to enable
the retaining ring 98 to be removably coupled to the central bore 85.
[0026] With reference to Fig. 6, a piloting flange 108c is coaxial with the central bore
85 to assist in aligning the bearing assembly 93 within the central bore 85 and with
a plurality of apertures 128 of a housing or gear case 120 of the compact accessory
gearbox 60. In one example, a gasket 104 includes a plurality of mounting bores 104a
that coaxially align with the plurality of mounting bores 90 to enable the mechanical
fastening assembly associated with the gearbox interface 84 to pass through the mounting
bores 104a and couple a flange 108b with the gasket 104 and the gearbox interface
84. The piloting flange 108c also defines a central bore 104b, which is sized to be
positioned about the central bore 85.
[0027] With reference back to Figs. 2 and 3, as the accessories 62-74 are generally known
to one skilled in the art, the accessories 62-74 will not be discussed in great detail
herein. Briefly, however, the starter valve 62 receives pressurized air from an auxiliary
power unit (APU) associated with the aircraft 8 to supply air to the starter turbine
64. The starter turbine 64 is coupled to the starter valve 62, and to the compact
accessory gearbox 60. The starter turbine 64 converts the pressurized air from the
APU into rotational energy, which is used to drive the towershaft 54, which via the
gears 56, 52, drives the high pressure driveshaft 46, and thus, the compressor 32
and the high pressure turbine 38 for starting the gas turbine engine 10 (Fig. 1).
The direct-current (DC) generator 66 is coupled to the compact accessory gearbox 60,
and is driven to convert mechanical energy received from the towershaft 54 into electricity
to power various electrical items onboard the aircraft 8. The hydraulic pump 68 is
coupled to the compact accessory gearbox 60 and is driven to provide high pressure
hydraulic fluid to one or more hydraulic components of the aircraft 8 and to power
a hydraulically actuated thrust reverser associated with the gas turbine engine 10.
The permanent magnet alternator 70 is coupled to the compact accessory gearbox 60,
and is driven to provide alternating current (AC) power to an engine control unit
associated with the gas turbine engine 10. The fuel control unit 72 is coupled to
the compact accessory gearbox 60 and is driven to provide fuel to the combustor 36
of the gas turbine engine 10 (Fig. 1). The fuel control unit 72 includes, but is not
limited to, a hydromechanical fuel control unit, an electronic fuel control unit,
a full authority digital engine control (FADEC), etc. The lubrication pump 74 is coupled
to the compact accessory gearbox 60 and driven to provide oil at the desired operating
pressure to various portions of the gas turbine engine 10. With reference to Fig.
3, the air-oil separator 76 is contained wholly within the compact accessory gearbox
60, and forms part of a gear train 122 associated with the compact accessory gearbox
60. The air-oil separator 76 is driven to separate air from oil within the compact
accessory gearbox 60.
[0028] With reference to Fig. 2, the compact accessory gearbox 60 is coupled to the gas
turbine engine 10 via one or more supports or struts 106. In this example, the compact
accessory gearbox 60 is coupled via two struts 106a, 106b, which extend outwardly
from the compact accessory gearbox 60 in a generally V-shape. The struts 106a, 106b
are composed of a suitable high strength material, such as a metal or metal alloy.
The struts 106a, 106b include one or more mounting bores 108 that receive a mechanical
fastener 108a, such as a bolt, to couple the struts 106a, 106b to the compact accessory
gearbox 60. The struts 106a, 106b also include a platform 110, which couples the struts
106a, 106b to the gas turbine engine 10. For example, the platform 110 may define
one or bores for receipt of a mechanical fastener to couple the struts 106a, 106b
to the gas turbine engine 10. Alternatively, the platform 110 may provide a surface
for spot welding the struts 106a, 106b. As a further example, the platform 110 may
be received in slots or interference-fit into a portion of the gas turbine engine
10.
[0029] With reference to Fig. 3, a bottom view of the compact accessory system 12 is shown
with the adaptors 80 removed from the accessories 62-74 for clarity. The compact accessory
gearbox 60 includes the housing or gear case 120 and the gear train 122. In this example,
the gear case 120 comprises a two-piece housing, with a first portion 124 and a second
portion 126 (Fig. 9; the second portion 126 is removed in Fig. 3 to illustrate the
gear train 122). The gear case 120 is composed of a metal, metal alloy or composite.
The first portion 124 and the second portion 126 are formed through any suitable technique,
such as casting, forging, machining, stamping, fiber layup, etc. Generally, the first
portion 124 comprises the plurality of apertures 128 to couple the gear train 122
to the various accessories 64-72. In this example, the first portion 124 includes
about seven apertures 128; however, the first portion 124 may include any desired
number of apertures 128. The plurality of apertures 128 are defined about the first
portion 124 so as to extend about a perimeter of the first portion 124, such that
the accessories 62-74 are arranged about a perimeter of the first portion 124. Generally,
the accessories 62-74 are arranged substantially circumferentially about the first
portion 124, which enables for a reduction in the volume of the engine nacelle N.
[0030] One or more of the plurality of apertures 128 is sized and shaped to receive a bearing
assembly 130. With reference to Fig. 7, the bearing assembly 130 includes a housing
132, a first bearing 134 and a second bearing 136. The housing 132 includes a lip
138, an annular flange 140 and a body 142. The housing 132 is circumferentially open
and receives the first bearing 134 and the second bearing 136. The lip 138 is defined
at a first end 132a of the housing 132, and has a reduced wall thickness compared
to the body 142 to enable the lip 138 to be received through the respective aperture
128 of the first portion 124 of the gear case 120. The annular flange 140 extends
circumferentially about the housing 132 and defines a plurality of coupling bores
140a. In this example, the annular flange 140 defines about three coupling bores 140a;
however, the annular flange 140 may define any number of coupling bores 140a. The
coupling bores 140a are generally spaced apart about a perimeter of the annular flange
140. The coupling bores 140a receive a suitable mechanical fastener, such as a bolt,
screw, rivet, etc. to couple the bearing assembly 130 to the gear case 120. The body
142 is substantially cylindrical, and receives the first bearing 134 and the second
bearing 136. The body 142 includes a retaining flange 142a, which is defined at a
second end 132b of the housing 132. The retaining flange 142a has a diameter, which
is less than a diameter of a reminder of the housing 132 to retain the first bearing
134 within the housing 132. One skilled in the art would appreciate that the body
142 may be designed and manufactured with any shape to properly interface with any
particular accessory 62-74.
[0031] The first bearing 134 and the second bearing 136 enable the rotation of a portion
of the gear train 122 to transfer torque between the towershaft 54, sleeve 55 and
the respective one of the accessories 62-74. The first bearing 134 and the second
bearing 136 are generally ball bearings or a combination of roller and ball bearings
that cooperate to receive a portion of the gear train 122 therethrough to enable the
portion of the gear train 122 to rotate relative to the gear case 120. The first bearing
134 generally includes a seal 134a, which faces the retaining flange 142a of the housing
132 when the first bearing 134 is coupled to the housing 132. Generally, the second
bearing 136 does not include a seal. By not including a seal with the second bearing
136, oil contained within the gear case 120 may lubricate both the first bearing 134
and the second bearing 136, while the seal 134a of the first bearing 134 prevents
the leakage of oil outside of the compact accessory gearbox 60. With reference to
Fig. 8, a top view of the compact accessory gearbox 60 illustrates that the bearing
assemblies 130 are generally coupled to each of the apertures 128, with the exception
of the aperture 128', which uses a different bearing configuration.
[0032] With reference to Fig. 9, the second portion 126 is shown in greater detail. The
second portion 126 may be generally planar and is removably coupled to the first portion
124. In one example, the first portion 124 is coupled to the second portion 126 via
a plurality of fastening bores that receive mechanical fasteners, such as bolts, screws,
etc. (not shown); however, the first portion 124 and the second portion 126 may be
coupled together via any suitable technique.
[0033] With reference back to Fig. 3, the gear train 122 is coupled to the respective accessories
64-72. The gear train 122 includes the shaft 150, a first accessory drive shaft 152,
a second accessory drive shaft 154, a third accessory drive shaft 156 and a fourth
accessory drive shaft 158. As will be discussed in greater detail herein, the gear
58 of the towershaft 54 is coupled to or meshingly engages with the shaft 150, and
the shaft 150 is coupled to or meshingly engages with the first accessory drive shaft
152, the second accessory drive shaft 154, the third accessory drive shaft 156 and
the fourth accessory drive shaft 158. As shown in Fig. 3, the first accessory drive
shaft 152 drives the lubrication pump 74, the second accessory drive shaft 154 drives
the fuel control unit 72, the third accessory drive shaft 156 drives the hydraulic
pump 68 and the fourth accessory drive shaft 158 drives the DC generator 66. The shaft
150 is driven by the starter turbine 64 during engine start-up, and drives the permanent
magnet alternator 70. The starter turbine 64 is generally decoupled from the shaft
150 after the start-up of the gas turbine engine 10 by an overspeed clutch. The shaft
150 also defines the air-oil separator 76.
[0034] With reference to Fig. 10, the gear train 122 is shown without the gear case 120,
the bearing assembly 130, the adaptors 80, the housing 59 and the accessories 62-74
for clarity. As shown, the shaft 150 has a shaft axis of rotation LR, which is substantially
transverse to the axis of rotation TR of the towershaft 54. The axis of rotation LR
of the shaft 150 is substantially parallel to the axis of rotation R of the gas turbine
engine 10 (Fig. 1). In certain embodiments, however, the axis of rotation LR of the
shaft 150 may not be substantially parallel to the axis of rotation R. The first accessory
drive shaft 152 has a first accessory axis of rotation R1, which is substantially
transverse to the axis of rotation LR of the shaft 150. The second accessory drive
shaft 154 has a second accessory axis of rotation R2, which is substantially transverse
or oblique to the axis of rotation LR of the shaft 150, and substantially transverse
or oblique to the first accessory axis of rotation R1. The third accessory drive shaft
156 has a third accessory axis of rotation R3, which is substantially transverse or
oblique to the axis of rotation LR of the shaft 150, and is substantially transverse
to the first accessory axis of rotation R1. The third accessory axis of rotation R3
is also substantially transverse to the second accessory axis of rotation R2, and
intersects the second accessory axis of rotation R2 along the axis of rotation LR
of the shaft 150. The fourth accessory drive shaft 158 has a fourth accessory axis
of rotation R4, which is substantially transverse or oblique to the axis of rotation
LR of the shaft 150, and is substantially transverse to the third accessory axis of
rotation R3. The fourth accessory axis of rotation R4 is substantially transverse
to the first accessory axis of rotation R1, and intersects the first accessory axis
of rotation R1 along the axis of rotation LR of the shaft 150. The fourth accessory
axis of rotation R4 is substantially transverse to the second axis of rotation R2.
[0035] Each of the first accessory axis of rotation R1, the second accessory axis of rotation
R2, the third accessory axis of rotation R3 and the fourth accessory axis of rotation
R4 define the centerlines for the respective accessory drive shafts 152-158. The shaft
axis of rotation LR defines the central axis for the shaft 150. With reference to
Figs. 10A and 10B, the first accessory axis of rotation R1, the accessory axis of
rotation R2, the third accessory axis of rotation R3 and the fourth accessory axis
of rotation R4 all substantially fit within an imaginary cone N. In this example,
the cone N has an angle that ranges from about zero degrees (a flat disk) to about
20 degrees. In one example, the cone N has an angle of about 12.5 degrees. The shaft
150 and the shaft axis of rotation LR are generally not on this cone N, as shown.
By defining the first accessory axis of rotation R1, the accessory axis of rotation
R2, the third accessory axis of rotation R3 and the fourth accessory axis of rotation
R4 on the cone N, the accessories 62-74 are mounted substantially circumferentially
around the compact accessory gearbox 60. In this example, the first accessory axis
of rotation R1 intersects the shaft axis of rotation LR at a first point P1, and the
fourth accessory axis of rotation R4 intersects the shaft axis of rotation LR at a
second point P2. Two of the accessory axes of rotation (i.e. the second accessory
axis of rotation R2 and the third accessory axis of rotation R3) intersect the shaft
axis of rotation LR at a third point P3. The point P1 is different than the point
P2, and is spaced apart from the point P2 along the shaft axis of rotation LR. The
point P3 is different than the points P1 and P2, and is spaced apart from the points
P1 and P2 along the shaft axis of rotation LR.
[0036] As best shown in Fig. 8, the first accessory axis of rotation R1 is spaced apart
along the perimeter of the gear case 120 from the second accessory axis of rotation
R2 by an angle α. In one example, the angle α is about 67 degrees to about 87 degrees.
Similarly, the third accessory axis of rotation R3 is spaced apart along the perimeter
of the gear case 120 from the fourth accessory axis of rotation R4 by the angle α.
The second accessory axis of rotation R2 is spaced apart from the shaft axis of rotation
LR by an angle β. In one example, the angle β is about 41 degrees to about 61 degrees.
Similarly, the third accessory axis of rotation R3 is spaced apart from the shaft
axis of rotation LR by the angle β. Thus, the accessory drive shafts 152-158 are generally
spaced apart about the gear case 120 in a substantially circular manner, which results
in the placement of the accessories 62-74 substantially circumferentially about the
gear case 120, allowing for a reduction in a space required in the engine nacelle
N for the accessories 62-74.
[0037] With additional reference to Fig. 9, one or more of the accessory axes of rotation
R1-R4 may be angled relative to the shaft axis of rotation LR. For example, each of
the first accessory axis of rotation R1, the second accessory axis of rotation R2,
the third accessory axis of rotation R3 and the fourth accessory axis of rotation
R4 are angularly offset from the shaft axis of rotation LR by an angle γ. Stated another
way, each of the first accessory axis of rotation R1, the second accessory axis of
rotation R2, the third accessory axis of rotation R3 and the fourth accessory axis
of rotation R4 are offset relative to an axis A of the compact accessory gearbox 60
by the angle γ. In one example, the angle γ is about 10 degrees to about 30 degrees.
By angling each of the first accessory drive shaft 152, the second accessory drive
shaft 154, the third accessory drive shaft 156 and the fourth accessory drive shaft
158 relative to the shaft 150, additional space saving may be achieved within the
engine nacelle N by enabling the accessories 62-74 to better follow the curvature
of the gas turbine engine 10.
[0038] With reference to Fig. 10, the shaft 150 is directly coupled to the towershaft 54,
and comprises a high speed shaft. For example, the shaft 150 rotates at about 18,500
revolutions per minute (rpm). The shaft 150 includes a first shaft gear 160, a second
shaft gear 162, a third shaft gear 164 and a fourth shaft gear 166 each arranged on
and coupled to a body 168 of the shaft 150. In one example, the first shaft gear 160,
second shaft gear 162, third shaft gear 164, fourth shaft gear 166 are coupled to
the body 168 via a splined joint, however, the first shaft gear 160, second shaft
gear 162, third shaft gear 164, fourth shaft gear 166 can be coupled to the body 168
via any technique, including, but not limited to, keyway, welding, machined as one
piece, 3D printed, etc. The first shaft gear 160, second shaft gear 162, third shaft
gear 164, fourth shaft gear 166 and the body 168 are generally formed of a metal or
metal alloy, and may be cast, machined, forged, etc. In this example, the first shaft
gear 160, second shaft gear 162, third shaft gear 164 and fourth shaft gear 166 each
comprise bevel gears having a respective plurality of bevel gear teeth 160a, 162a,
164a, 166a. The plurality of bevel gear teeth 160a-166a are defined about a perimeter
or circumference of each of the shaft gears 160-166. The plurality of bevel gear teeth
160a of the first shaft gear 160 are coupled to and meshingly engage with the plurality
of bevel gear teeth 58a of the gear 58 of the towershaft 54 and the sleeve 55. The
plurality of bevel gear teeth 162a of the second shaft gear 162 are coupled to and
meshingly engage with a plurality of bevel gear teeth 172a of a first accessory gear
172 coupled to the first accessory drive shaft 152. The plurality of bevel gear teeth
164a of the third shaft gear 164 are coupled to and meshingly engage with a plurality
of bevel gear teeth 178a of a fourth accessory gear 178 coupled to the fourth accessory
drive shaft 158. The plurality of bevel gear teeth 166a of the fourth shaft gear 166
are coupled to and meshingly engage with a plurality of bevel gear teeth 174a of a
second accessory gear 174 coupled to the second accessory drive shaft 154, and are
coupled to and meshingly engage with a plurality of bevel gear teeth 176a of a third
accessory gear 176 coupled to the third accessory drive shaft 156. In one example,
the first shaft gear 160 also includes a projection 160b, which aids in coupling the
shaft 150 to the gear case 120. Similarly, the fourth shaft gear 166 includes a projection
166b, which aids in coupling the shaft 150 to the gear case 120.
[0039] One or more of the shaft gears 160-166 may be separated by one or more spacers 180.
In this example, the first shaft gear 160 and the second shaft gear 162 are separated
by a spacer 180a, and the second shaft gear 162 and the third shaft gear 164 are separated
by a spacer 180b. The spacer 180a may have a length along the shaft axis of rotation
LR, which is greater than a length of the spacer 180b along the shaft axis of rotation
LR. The spacers 180a, 180b may be composed of any suitable material, such as a metal
or metal alloy, and may be stamped, cast, machined, etc. The spacers 180a, 180b provide
clearance for the coupling of the gear 58, the first accessory gear 172 and the fourth
accessory gear 178 for rotation with the shaft 150.
[0040] With reference to Fig. 11, the body 168 of the shaft 150 includes a first coupling
portion 182, a second coupling portion 184 and the air-oil separator 76 defined between
a first end 168a and a second end 168b of the body 168. The first end 168a of the
body 168 is coupled to the starter turbine 64, and the second end 168b of the body
168 is coupled to the permanent magnet alternator 70. The body 168 of the shaft 150
is formed of a metal or metal alloy, and may be cast, machined, stamped, forged, etc.
In one example, the first coupling portion 182 extends for a first distance along
a longitudinal axis L4 of the shaft 150, which is different than a second distance
that the second coupling portion 184 extends along the longitudinal axis L4. In this
example, the first distance is greater than the second distance. The first coupling
portion 182 includes a first enlarged portion 186 and a first plurality of splines
188. The first enlarged portion 186 is defined adjacent to the air-oil separator 76,
and may be defined by material removal along a remainder of the body 168. In this
regard, the first enlarged portion 186 generally has a larger diameter than a remainder
of the body 168, with the exception of a second enlarged portion 190 associated with
the second coupling portion 184. The first enlarged portion 186 and the second enlarged
portion 190 each have substantially the same diameter D1, which is different than
a diameter D2 of the remainder of the body 168. In this example, the diameter D1 is
greater than the diameter D2. The first enlarged portion 186 and the second enlarged
portion 190 provide stops that prevent the further advancement of the third shaft
gear 164 and the fourth shaft gear 166 respectively, along the body 168 during assembly
of the third shaft gear 164 and the fourth shaft gear 166 to the body 168. Thus, each
of the third shaft gear 164 and the fourth shaft gear 166 have an inner diameter,
which is less than the diameter D1.
[0041] The first plurality of splines 188 are defined slightly past the first enlarged portion
186 so as to extend slightly beyond the first enlarged portion 186 (i.e. the first
plurality of splines 188 extend past the first enlarged portion 186 so as to abut
the air-oil separator 76) and through the first enlarged portion 186 towards the first
end 168a of the body 168. Generally, the first plurality of splines 188 extend for
a length along the longitudinal axis L4 that enables the first shaft gear 160, spacer
180a, second shaft gear 162, spacer 180b and third shaft gear 164 to be coupled to
the body 168. In this regard, each of the first shaft gear 160, spacer 180a, second
shaft gear 162, spacer 180b and third shaft gear 164 include a plurality of mating
splines 192. Each of the plurality of mating splines 192 cooperate with the first
plurality of splines 188 to couple the first shaft gear 160, spacer 180a, second shaft
gear 162, spacer 180b and third shaft gear 164 to the body 168, while inhibiting relative
rotation between the body 168 and the first shaft gear 160, spacer 180a, second shaft
gear 162, spacer 180b and third shaft gear 164. Stated another way, the plurality
of mating splines 192 and the first plurality of splines 188 couple the first shaft
gear 160, spacer 180a, second shaft gear 162, spacer 180b and third shaft gear 164
to the body 168 such that the first shaft gear 160, spacer 180a, second shaft gear
162, spacer 180b and third shaft gear 164 rotate with the body 168.
[0042] The plurality of splines 188 comprise any number of splines defined about a circumference
of the shaft 150, and may comprise a single spline, if desired. Generally, the plurality
of splines 188 are defined by machining or cutting the plurality of splines 188 into
the body 168, however, the plurality of splines 188 may be formed through any desired
technique. The plurality of mating splines 192 may be defined along an inner diameter
of each of the first shaft gear 160, spacer 180a, second shaft gear 162, spacer 180b
and third shaft gear 164 during the formation of the first shaft gear 160, spacer
180a, second shaft gear 162, spacer 180b and third shaft gear 164. It will be understood,
however, that the spacer 180a and/or the spacer 180b need not include the plurality
of mating splines 192, and can comprise a generally smooth or uniform inner diameter.
Generally, the plurality of mating splines 192 extend along an entirety of the inner
diameter of each of the first shaft gear 160, spacer 180a, second shaft gear 162,
spacer 180b and third shaft gear 164 to facilitate the advancement of each of the
first shaft gear 160, spacer 180a, second shaft gear 162, spacer 180b and third shaft
gear 164 along the first coupling portion 182. It should be noted that while the first
shaft gear 160, spacer 180a, second shaft gear 162, spacer 180b and third shaft gear
164 are each described herein as including the plurality of mating splines 192, the
first shaft gear 160, spacer 180a, second shaft gear 162, spacer 180b and third shaft
gear 164 may include any number of mating splines 192 that cooperate to couple the
first shaft gear 160, spacer 180a, second shaft gear 162, spacer 180b and third shaft
gear 164 to the body 168. Moreover, the plurality of mating splines 192 may be formed
to have an interference fit with the first plurality of splines 188, if desired.
[0043] The second coupling portion 184 includes the second enlarged portion 190 and a second
plurality of splines 194. The second enlarged portion 190 is defined adjacent to the
air-oil separator 76, and is defined so to be substantially opposite the first enlarged
portion 186. The second enlarged portion 190 may be defined by material removal along
a remainder of the body 168. The second plurality of splines 194 are defined slightly
past the second enlarged portion 190 so as to extend slightly beyond the second enlarged
portion 190 (i.e. the second plurality of splines 194 extend past the second enlarged
portion 190 so as to abut the air-oil separator 76) and through the second enlarged
portion 190 towards the second end 168b of the body 168. Generally, the second plurality
of splines 194 extend for a length along the longitudinal axis L4 that enables the
fourth shaft gear 166 to be coupled to the body 168. In this regard, generally, the
fourth shaft gear 166 includes a second plurality of mating splines 196. Each of the
second plurality of mating splines 196 cooperate with the second plurality of splines
194 to couple the fourth shaft gear 166 to the body 168, while inhibiting relative
rotation between the body 168 and the fourth shaft gear 166. Stated another way, the
second plurality of mating splines 196 and the second plurality of splines 194 couple
the fourth shaft gear 166 to the body 168 such that the fourth shaft gear 166 rotates
with the body 168.
[0044] The second plurality of splines 194 comprise any number of splines defined about
a circumference of the shaft 150, and may comprise a single spline, if desired. Generally,
the second plurality of splines 194 are defined by machining or cutting the second
plurality of splines 194 into the body 168, however, the second plurality of splines
194 may be formed through any desired technique. The second plurality of mating splines
196 may be defined along an inner diameter the fourth shaft gear 166 during the formation
of the fourth shaft gear 166. Generally, the second plurality of mating splines 196
extend along an entirety of the inner diameter of the fourth shaft gear 166 to facilitate
the advancement of the fourth shaft gear 166 along the second coupling portion 184.
It should be noted that while the fourth shaft gear 166 is described herein as including
the second plurality of mating splines 196, the fourth shaft gear 166 may include
any number of mating splines 196 that cooperate to couple the fourth shaft gear 166
to the body 168. Moreover, the second plurality of mating splines 196 may be formed
to have an interference fit with the second plurality of splines 194, if desired.
[0045] The air-oil separator 76 is defined through the body 168 between the first coupling
portion 182 and the second coupling portion 184. In this example, the air-oil separator
76 comprises a plurality of bores 198 defined through the body 168 such that each
of the plurality of bores 198 are in communication with an inner channel 200 defined
in the body 168, as shown in Fig. 12. In this regard, the body 168 comprises a substantially
hollow shaft from the second enlarged portion 190 to the first end 168a of the body
168. Stated another way, the body 168 is milled or bored to define the inner channel
200, which extends through the body 168 from the first end 168a to the second enlarged
portion 190. The inner channel 200 enables the separation of the air from the oil
within the gear case 120 as the shaft 150 rotates within the gear case 120. Generally,
the plurality of bores 198 centrifugates oil from the air, with the air separated
from the oil remaining within the inner channel 200 to be drawn from the gear case
120 via a plurality of bores 204 defined near the first end 168a of the shaft 150.
An additional mesh or screen 222 may be packed inside of the inner channel 200 to
increase an available surface area within the inner channel 200, which improves the
air oil separation effectiveness. The plurality of bores 198 are generally defined
about an entirety of the circumference of the body 168 to define the air-oil separator
76, and may be arranged in a repeating pattern, or may be uniquely defined as desired
along the circumference. A sump pump (not shown) may be coupled to the gear case 120
to remove the separated oil that generally collects along a surface 126a of the second
portion 126 of the gear case 120. In certain examples, the body 168 may also define
a second counterbore or inner channel 202 defined from the second end 168b to the
second coupling portion 184 to reduce a weight of the shaft 150. The second counterbore
or inner channel 202 may be defined into the body 168 via milling or boring at the
second end 168b to the second coupling portion 184.
[0046] With reference back to Fig. 11, the body 168 also includes the plurality of bores
204 defined near the first end 168a. The air separated by the air-oil separator 76
flows from the plurality of bores 198 through the inner channel 200 to the plurality
of bores 204. The air exits the shaft 150, and thus, the gear case 120 via the plurality
of bores 204. The plurality of bores 204 are in communication with the inner channel
200 and a shaft bearing assembly 206 to bleed air collected by the air-oil separator
76 out of the gear case 120. In this regard, with additional reference to Fig. 12,
the shaft 150 may be assembled within the gear case 120 with one of the bearing assemblies
130 coupled about or near the second end 168b to couple the shaft 150 within the gear
case 120 for rotation, while the first end 168a may be coupled to the gear case 120
via the shaft bearing assembly 206 for rotation. In one example, the bearing assembly
130 bears against the projection 166b of the fourth shaft gear 166 when the bearing
assembly 130 is coupled to the gear case 120 and the shaft 150 to maintain the assembly
of the shaft 150 within the gear case 120. The bearing assembly 206 bears against
the projection 160b of the first shaft gear 160 when the bearing assembly 206 is coupled
to the gear case 120 to maintain the assembly of the shaft 150 within the gear case
120.
[0047] As the shaft bearing assembly 206 may be substantially similar to the bearing assembly
130 described with regard to Fig. 7, the same reference numerals will be used to denote
the same or similar components. In one example, the shaft bearing assembly 206 includes
a housing 208, the first bearing 134, the second bearing 136 and a spacer 210. The
housing 208 includes the lip 138, the annular flange 140 and a body 212. The housing
208 is circumferentially open and receives the first bearing 134 and the second bearing
136. The lip 138 is defined at a first end 208a of the housing 208, and the annular
flange 140 extends circumferentially about the housing 208 and defines the plurality
of coupling bores 140a. The body 212 is substantially cylindrical, and receives the
first bearing 134 and the second bearing 136. The body 212 includes a retaining flange
212a, which is defined at a second end 208b of the housing 208. The retaining flange
212a has a diameter, which is less than a diameter of a reminder of the housing 208
to retain the first bearing 134 within the housing 208.
[0048] The spacer 210 is positioned between the first bearing 134 and the second bearing
136 within the housing 208. The spacer 210 includes a plurality of slots 210a defined
about a circumference of the spacer 210, which are in fluid communication with the
plurality of bores 204 of the body 168, as shown in Fig. 12. The plurality of slots
210a enable the air collected via the air-oil separator 76 to be bleed out of the
compact accessory gearbox 60, as the spacer 210 is located external to the gear case
120 when the bearing assembly 206 is coupled to the gear case 120.
[0049] With reference back to Fig. 10, the first accessory drive shaft 152, the second accessory
drive shaft 154, the third accessory drive shaft 156 and the fourth accessory drive
shaft 158 are each coupled directly to the shaft 150 to be driven directly by the
shaft 150. Each of the first accessory drive shaft 152, the second accessory drive
shaft 154, the third accessory drive shaft 156 and the fourth accessory drive shaft
158 are composed of a suitable metal or metal alloy, and may be cast, machined, forged,
etc. The first accessory drive shaft 152 includes the first accessory gear 172 defined
about a first end 152a of the first accessory drive shaft 152. The first accessory
gear 172 is composed of a suitable metal or metal alloy, and may be cast, machined,
forged, etc. and coupled to the first accessory drive shaft 152. Further, the first
accessory gear 172 may be integrally formed with the first accessory drive shaft 152.
The first accessory gear 172 comprises a bevel gear that has the plurality of bevel
gear teeth 172a. The plurality of bevel gear teeth 172a are defined about a perimeter
or circumference of the first accessory gear 172, and the plurality of bevel gear
teeth 172a meshingly engage the plurality of bevel gear teeth 162a of the second shaft
gear 162. The first accessory drive shaft 152 comprises a lower speed drive shaft,
and is driven to rotate at about 8,500 rpm. Stated another way, the first accessory
drive shaft 152 rotates at a speed, which is different than a rotational speed of
the shaft 150 and is generally less than the rotational speed of the shaft 150. The
first accessory drive shaft 152 is coupled to the lubrication pump 74 at a second
end 152b. The first accessory drive shaft 152 also includes a bearing stop portion
214. The bearing stop portion 214 is defined as an area along the first accessory
drive shaft 152 that has an increased or greater diameter than a reminder of the first
accessory drive shaft 152 to provide a stop for the bearing assembly 130. The bearing
stop portion 214 is defined near the first end 152a, and when assembled into the gear
case 120, the bearing stop portion 214 contacts the second bearing 136 of the bearing
assembly 130.
[0050] The second accessory drive shaft 154 includes the second accessory gear 174 defined
about a first end 154a of the second accessory drive shaft 154. The second accessory
gear 174 is composed of a suitable metal or metal alloy, and may be cast, machined,
forged, etc. and coupled to the second accessory drive shaft 154. Further, the second
accessory gear 174 may be integrally formed with the second accessory drive shaft
154. The second accessory gear 174 comprises a bevel gear that has the plurality of
bevel gear teeth 174a. The plurality of bevel gear teeth 174a are defined about a
perimeter or circumference of the second accessory gear 174, and the plurality of
bevel gear teeth 174a meshingly engage the plurality of bevel gear teeth 166a of the
fourth shaft gear 166. The second accessory drive shaft 154 comprises a lower speed
drive shaft, and is driven to rotate at about 8,500 rpm. Stated another way, the second
accessory drive shaft 154 rotates at a speed, which is different than the rotational
speed of the shaft 150 and is generally less than the rotational speed of the shaft
150. The second accessory drive shaft 154 is coupled to the fuel control unit 72 at
a second end 154b. The second accessory drive shaft 154 also includes a second bearing
stop portion 216. The second bearing stop portion 216 is defined as an area along
the second accessory drive shaft 154 that has an increased or greater diameter than
a reminder of the second accessory drive shaft 154 to provide a stop for the bearing
assembly 130. The second bearing stop portion 216 is defined near the first end 154a,
and when assembled into the gear case 120, the second bearing stop portion 216 contacts
the second bearing 136 of the bearing assembly 130.
[0051] The third accessory drive shaft 156 includes the third accessory gear 176 defined
about a first end 156a of the third accessory drive shaft 156. The third accessory
gear 176 is composed of a suitable metal or metal alloy, and may be cast, machined,
forged, etc. and coupled to the third accessory drive shaft 156. Further, the third
accessory gear 176 may be integrally formed with the third accessory drive shaft 156.
The third accessory gear 176 comprises a bevel gear that has the plurality of bevel
gear teeth 176a. The plurality of bevel gear teeth 176a are defined about a perimeter
or circumference of the third accessory gear 176, and the plurality of bevel gear
teeth 176a meshingly engage the plurality of bevel gear teeth 166a of the fourth shaft
gear 166. The third accessory drive shaft 156 comprises a lower speed drive shaft,
and is driven to rotate at about 8,500 rpm. Stated another way, the third accessory
drive shaft 156 rotates at a speed, which is different than the rotational speed of
the shaft 150 and is generally less than the rotational speed of the shaft 150. The
third accessory drive shaft 156 is coupled to the hydraulic pump 68 at a second end
156b. The third accessory drive shaft 156 also includes a third bearing stop portion
218. The third bearing stop portion 218 is defined as an area along the third accessory
drive shaft 156 that has an increased or greater diameter than a reminder of the third
accessory drive shaft 156 to provide a stop for the bearing assembly 130. The third
bearing stop portion 218 is defined near the first end 156a, and when assembled into
the gear case 120, the third bearing stop portion 218 contacts the second bearing
136 of the bearing assembly 130.
[0052] The fourth accessory drive shaft 158 includes the fourth accessory gear 178 defined
about a first end 158a of the fourth accessory drive shaft 158. The fourth accessory
gear 178 is composed of a suitable metal or metal alloy, and may be cast, machined,
forged, etc. and coupled to the fourth accessory drive shaft 158. Further, the fourth
accessory gear 178 may be integrally formed with the fourth accessory drive shaft
158. The fourth accessory gear 178 comprises a bevel gear that has the plurality of
bevel gear teeth 178a. The plurality of bevel gear teeth 178a are defined about a
perimeter or circumference of the fourth accessory gear 178, and the plurality of
bevel gear teeth 178a meshingly engages the plurality of bevel gear teeth 164a of
the third shaft gear 164. The fourth accessory drive shaft 158 comprises a high speed
drive shaft, and is driven to rotate at about 18,500 rpm. Stated another way, the
fourth accessory drive shaft 158 rotates at a speed, which is about the same as the
rotational speed of the shaft 150. Thus, generally, the fourth accessory gear 178
has a diameter that is different or greater than a diameter of the first accessory
gear 172, second accessory gear 174 and third accessory gear 176. The fourth accessory
drive shaft 158 is coupled to the DC generator 66 at a second end 158b. The fourth
accessory drive shaft 158 also includes a fourth bearing stop portion 220. The fourth
bearing stop portion 220 is defined as an area along the fourth accessory drive shaft
158 that has an increased or greater diameter than a remainder of the fourth accessory
drive shaft 158 to provide a stop for the bearing assembly 130. The fourth accessory
drive shaft 158 is defined near the first end 158a, and when assembled into the gear
case 120, the fourth accessory drive shaft 158 contacts the second bearing 136 of
the bearing assembly 130.
[0053] Generally, the gear case 120 is not filled with oil to lubricate the gear train 122.
In this example, with reference to Figs. 1B and 13, oil or lubricating fluid for the
compact accessory gearbox 60 is also received from an oil tank 232. The oil tank 232
is disposed near the compact accessory gearbox 60 within the engine nacelle N. One
or more conduits are coupled between the oil tank 232 and the compact accessory gearbox
60 to enable oil from the oil tank 232 to flow to the gear case 120 to lubricate the
gear train 122. In Fig. 1B, the oil is contained in the oil tank 232, and flows to
the oil pump 74, through an oil filter 234, and through an air/oil cooler 235 that
delivers the oil or lubricating fluid to the gear case 120 of the compact accessory
gearbox 60 to lubricate the gear train 122. The oil is scavenged from the compact
accessory gearbox 60 and returns to the oil tank 232. Thus, the oil tank 232 and the
compact accessory gearbox 60 may include one or more fittings, hoses, control valves
and ports, which fluidly couple the conduits to the oil tank 232 and the compact accessory
gearbox 60. In this example, the oil tank 232 is separate from the compact accessory
gearbox 60. With reference to Fig. 13, the oil tank 232 may include the oil filter
234, a fuel heater/oil cooler 236 and some accessories, including, plugs, fittings,
hoses and ports (not shown).
[0054] In order to assemble the shaft 150, in one example, with the body 168 of the shaft
150 machined to include the first coupling portion 182, the second coupling portion
184 and the air-oil separator 76, the third shaft gear 164 is slid over the first
end 168a of the body 168 until the third shaft gear 164 abuts the first enlarged portion
186. The fourth shaft gear 166 is slid over the second end 168b of the body 168 until
the fourth shaft gear 166 abuts the second enlarged portion 190. The spacer 180b is
slid over the first end 168a until the spacer 180b abuts the third shaft gear 164.
The second shaft gear 162 is slid over the first end 168a until the second shaft gear
162 abuts the spacer 180b. The spacer 180a is slid over the first end 168a until the
spacer 180a abuts the second shaft gear 162. The first shaft gear 160 is slid over
the first end 168a until the first shaft gear 160 abuts the spacer 180a.
[0055] In one example, in order to assemble the compact accessory gearbox 60, the first
accessory drive shaft 152, the second accessory drive shaft 154, the third accessory
drive shaft 156 and the fourth accessory drive shaft 158 are each positioned through
a respective one of the plurality of apertures 128 defined through the first portion
124 of the gear case 120. Respective ones of the bearing assemblies 130 are coupled
to each of the first accessory drive shaft 152, the second accessory drive shaft 154,
the third accessory drive shaft 156 and the fourth accessory drive shaft 158, and
are slid over the respective second ends 152b, 154b, 156b, 158b until the bearing
assembly 130 contacts the respective bearing stop portion 214, 216, 218, 220. Upon
contacting the bearing stop portions 214, 216, 218, 220, a plurality of mechanical
fasteners are inserted through the coupling bores 140a to couple the bearing assemblies
130 to the first portion 124, thereby coupling the first accessory drive shaft 152,
the second accessory drive shaft 154, the third accessory drive shaft 156 and the
fourth accessory drive shaft 158 to the first portion 124 of the gear case 120.
[0056] With the shaft 150 assembled, the shaft 150 is inserted through the aperture 128"
until the fourth shaft gear 166 contacts a surface of the first portion 124. The bearing
assembly 130 is slid over the second end 168b of the body 168 and the bearing assembly
206 is slid over the first end 168a of the body 168 such that the plurality of bores
204 are aligned with the plurality of slots 210a in the spacer 210 to enable air to
vent from the gear case 120. A plurality of mechanical fasteners are inserted into
the coupling bores 140a to couple the bearing assembly 130 and the bearing assembly
206 to the first portion 124 of the gear case 120. The second portion 126 is positioned
over the first portion 124 and coupled to the first portion 124 via one or more mechanical
fasteners.
[0057] With the first portion 124 and the second portion 126 of the gear case 120 coupled
together, the gear case 120 is positioned such that the second end 54b of the towershaft
54 is received within the aperture 128' and the gear 58 of the sleeve 55 meshingly
engages with the shaft 150. The housing 59 of the towershaft 54 is coupled to the
first portion 124 of the gear case 120 via one or more mechanical fasteners, and the
struts 106a, 106b are coupled to the gas turbine engine 10 to couple the compact accessory
gearbox 60 to the gas turbine engine 10.
[0058] With the compact accessory gearbox 60 coupled to the gas turbine engine 10, the accessories
62-74 are coupled to the first accessory drive shaft 152, the second accessory drive
shaft 154, the third accessory drive shaft 156, the fourth accessory drive shaft 158
and the shaft 150 via the adaptors 80. The compact accessory gearbox 60 has a volume
that is about 1/18
th the size of a conventional gearbox, and provides about a 93 percent reduction in
space required within the engine nacelle N for the compact accessory gearbox 60 when
compared to a conventional gearbox.
[0059] In one example, with the high pressure driveshaft 46 driving or rotating the towershaft
54 about the towershaft axis of rotation TR, the torque from the high pressure driveshaft
46 is transmitted through the towershaft 54 and into the gear train 122 via the meshing
engagement of the gear 58 with the first shaft gear 160. Thus, the rotation of the
towershaft 54 rotates the shaft 150 about the shaft axis of rotation LR. The rotation
of the shaft 150 drives or rotates the first accessory drive shaft 152 (via the engagement
between the second shaft gear 162 and the first accessory gear 172); drives or rotates
the second accessory drive shaft 154 (via the engagement between the fourth shaft
gear 166 and the second accessory gear 174); drives or rotates the third accessory
drive shaft 156 (via the engagement between the fourth shaft gear 166 and the third
accessory gear 176); and drives or rotates the fourth accessory drive shaft 158 (via
the engagement between the third shaft gear 164 and the fourth accessory gear 178).
The rotation of the shaft 150 also separates the air from the oil within the compact
accessory gearbox 60, which is bled out through the plurality of bores 204 and slots
210a. The rotation of the drive shafts 152-158 provides input torque the respective
accessories 74, 72, 68 and 66 for operating the respective accessories 74, 72, 68
and 66. Moreover, the rotation of the shaft 150 provides input torque to the permanent
magnet alternator 70.
[0060] Prior to a start-up of the gas turbine engine 10, the starter valve 62 may direct
pressurized air to the starter turbine 64. The starter turbine 64 rotates the shaft
150, and the engagement between the first shaft gear 160 and the gear 58 transmits
the torque from the starter turbine 64 to the high pressure driveshaft 46, which causes
the high pressure driveshaft 46 to rotate. The rotation of the high pressure driveshaft
46 drives the compressor 32 and the high pressure turbine 38, thereby enabling a start-up
of the gas turbine engine 10.
[0061] It should be noted that the compact accessory gearbox 60 may be configured in various
different ways. For example, with reference to Fig. 14, a simplified view of a compact
accessory gearbox 300 is shown in which the bearing assemblies 130, 206, adaptors
80 and accessories 62-74 are removed for clarity. As the compact accessory gearbox
300 is similar to the compact accessory gearbox 60 discussed with regard to Figs.
1-13, only the differences between the compact accessory gearbox 300 and the compact
accessory gearbox 60 will be discussed in detail herein, with the same reference numerals
used to denote the same or substantially similar components. The compact accessory
gearbox 300 can be employed with the gas turbine engine 10 to transmit torque from
the towershaft 54 to the accessories 64-74.
[0062] The compact accessory gearbox 300 includes the gear case 120 and a gear train 302.
The gear train 302 is coupled to the respective accessories 64-74. Similar to the
compact accessory gearbox 60, the accessories 62-74 are arranged substantially circumferentially
about the first portion 124 of the compact accessory gearbox 300, which enables for
a reduction in the volume of the engine nacelle N. The gear train 302 includes a shaft
304, a first accessory drive shaft 306, a second accessory drive shaft 308, a third
accessory drive shaft 310, a fourth accessory drive shaft 312 and a fifth accessory
drive shaft 314. As will be discussed in greater detail herein, the gear 58 of the
sleeve 55 is coupled to or meshingly engages with the shaft 304, and the shaft 304
is coupled to or meshingly engages with the first accessory drive shaft 306 and the
fifth accessory drive shaft 314. Generally, the first accessory drive shaft 306 drives
the lubrication pump 74, the second accessory drive shaft 308 drives the fuel control
unit 72, the third accessory drive shaft 310 drives the drives the permanent magnet
alternator 70, the fourth accessory drive shaft 312 drives the hydraulic pump 68 and
the fifth accessory drive shaft 314 drives the DC generator 66. The shaft 304 is driven
by the starter turbine 64.
[0063] With continued reference to Fig. 14, the shaft 304 has a shaft axis of rotation LR2,
which is substantially transverse to the axis of rotation TR of the towershaft 54.
The axis of rotation LR of the shaft 304 is substantially parallel to the axis of
rotation R of the gas turbine engine 10 (Fig. 1). In certain embodiments, however,
the axis of rotation LR of the shaft 304 may not be substantially parallel to the
axis of rotation R. The first accessory drive shaft 306 has a first accessory axis
of rotation R1a, which is substantially transverse to the axis of rotation LR2 of
the shaft 304. The second accessory drive shaft 308 has a second accessory axis of
rotation R2a, which is substantially transverse to the axis of rotation LR2 of the
shaft 304, and substantially transverse to the first accessory axis of rotation R1a.
The third accessory drive shaft 310 has a third accessory axis of rotation R3a, which
is substantially parallel to the axis of rotation LR2 of the shaft 304, and is substantially
transverse to the first accessory axis of rotation R1a. The third accessory axis of
rotation R3a is also substantially transverse to the second accessory axis of rotation
R2a. The fourth accessory drive shaft 312 has a fourth accessory axis of rotation
R4a, which is substantially transverse to the axis of rotation LR2 of the shaft 304,
and is substantially transverse to the third accessory axis of rotation R3a. The fourth
accessory axis of rotation R4a is substantially transverse to the first accessory
axis of rotation R1a. The fourth accessory axis of rotation R4a is substantially transverse
to the second axis of rotation R2a. The fifth accessory drive shaft 314 has a fifth
accessory axis of rotation R5a, which is substantially transverse to the axis of rotation
LR2 of the shaft 304, and is substantially transverse to the third accessory axis
of rotation R3a. The fifth accessory axis of rotation R5a is substantially transverse
to the second accessory axis of rotation R2a, and is substantially transverse to the
first accessory axis of rotation R1a. The fifth accessory axis of rotation R5a is
substantially transverse to the fourth axis of rotation R4a. In this example, each
of the axes of rotation LR2, R1a-R5a, which each comprise centerlines, intersect at
a single common point P. The axes of rotation TR and R5a also intersect each, but
may not necessarily intersect each other at point P.
[0064] Each of the first accessory axis of rotation R1a, the second accessory axis of rotation
R2a, the third accessory axis of rotation R3a, the fourth accessory axis of rotation
R4a and the fifth accessory axis of rotation R5a define the centerlines for the respective
accessory drive shafts 306-314. The shaft axis of rotation LR2 defines the central
axis for the shaft 304.
[0065] In this example, the first accessory axis of rotation R1a is spaced apart along the
perimeter of the gear case 120 from the second accessory axis of rotation R2a by the
angle α. In one example, the angle α1 is about 67 degrees to about 87 degrees. Similarly,
the fifth accessory axis of rotation R5a is spaced apart along the perimeter of the
gear case 120 from the fourth accessory axis of rotation R4a by the angle α. The second
accessory axis of rotation R2a is spaced apart from the third accessory axis of rotation
R3a by the angle β. Similarly, the third accessory axis of rotation R3a is spaced
apart from the fourth axis of rotation R4a by the angle β. Thus, the accessory drive
shafts 306-314 are generally spaced apart about the gear case 120 in a substantially
circular manner, which results in the placement of the accessories 62-74 substantially
circumferentially about the gear case 120, allowing for a reduction in a space required
in the engine nacelle N for the accessories 62-74. In addition, one or more of the
accessory axes of rotation R1a-R5a may be angled relative to the shaft axis of rotation
LR2, if desired.
[0066] The shaft 304 is directly coupled to the sleeve 55, and comprises a high speed shaft.
For example, the shaft 304 rotates at about 18,500 revolutions per minute (rpm). The
shaft 304 includes a first shaft gear 320, a second shaft gear 322 and a third shaft
gear 324 each arranged on and coupled to a body 326 of the shaft 304. The first shaft
gear 320, second shaft gear 322, third shaft gear 324 and the body 326 are generally
formed of a metal or metal alloy, and may be cast, machined, forged, etc. In this
example, the first shaft gear 320, second shaft gear 322 and third shaft gear 324
each comprise bevel gears having a respective plurality of bevel gear teeth 320a-324a.
The plurality of bevel gear teeth 320a-324a are each defined about a perimeter or
circumference of each of the shaft gears 320-324. The plurality of bevel gear teeth
320a of the first shaft gear 320 are coupled to and meshingly engage with the plurality
of bevel gear teeth 58a of the gear 58 of the sleeve 55. The plurality of bevel gear
teeth 322a of the second shaft gear 322 are coupled to and meshingly engage with a
plurality of bevel gear teeth 172a of the first accessory gear 172 coupled to the
first accessory drive shaft 306. The plurality of bevel gear teeth 324a of the third
shaft gear 324 are coupled to and meshingly engage with a plurality of bevel gear
teeth 178a of the fourth accessory gear 178, which is coupled to the fifth accessory
drive shaft 314. In one example, the first shaft gear 320 also includes a flat surface
320b, which aids in coupling the shaft 304 to the gear case 120 by providing a coupling
surface for a respective one of the bearing assemblies 130, for example.
[0067] One or more of the shaft gears 320-324 may be separated by one or more spacers 328.
In this example, the first shaft gear 320 and the second shaft gear 322 are separated
by a spacer 328a, and the second shaft gear 322 and the third shaft gear 324 are separated
by a spacer 328b. The spacer 328a may have a length along the shaft axis of rotation
LR2, which is greater than a length of the spacer 328b along the shaft axis of rotation
LR2. The spacers 328a, 328b may be composed of any suitable material, such as a metal
or metal alloy, and may be stamped, cast, machined, etc. The spacers 328a, 328b provided
clearance for the coupling of the gear 58, the first accessory gear 172 and the fourth
accessory gear 178 for rotation with the shaft 150.
[0068] The body 326 of the shaft 304 is formed of a metal or metal alloy, and may be cast,
machined, stamped, forged, etc. Although not illustrated herein, the body 326 may
include the first coupling portion 182 and the second coupling portion 184, if desired.
The body 326 includes a first end 326a opposite a second end 326b. The third shaft
gear 324 is coupled at the first end 326a and the starter turbine 64 is coupled to
the second end 326b.
[0069] The first accessory drive shaft 306 and the fifth accessory drive shaft 314 are each
coupled directly to the shaft 304 to be driven directly by the shaft 304. Each of
the first accessory drive shaft 306, the second accessory drive shaft 308, the third
accessory drive shaft 310, the fourth accessory drive shaft 312 and the fifth accessory
drive shaft 314 are composed of a suitable metal or metal alloy, and may be cast,
machined, forged, etc. The first accessory drive shaft 306 includes the first accessory
gear 172 defined about a first end 306a of the first accessory drive shaft 306, which
meshingly engages the second shaft gear 322. The first accessory drive shaft 306 comprises
a lower speed drive shaft, and is driven to rotate at about 8,500 rpm. Stated another
way, the first accessory drive shaft 306 rotates at a speed, which is different than
a rotational speed of the shaft 304 and is generally less than the rotational speed
of the shaft 304. The first accessory drive shaft 306 is coupled to the lubrication
pump 74 at a second end 306b.
[0070] The second accessory drive shaft 308 includes the second accessory gear 174 defined
about a first end 308a of the second accessory drive shaft 308. The second accessory
gear 174 is coupled to and meshingly engages the first accessory gear 172. The second
accessory drive shaft 308 comprises a lower speed drive shaft, and is driven to rotate
at about 8,500 rpm. Stated another way, the second accessory drive shaft 308 rotates
at a speed, which is different than the rotational speed of the shaft 304 and is generally
less than the rotational speed of the shaft 304. The second accessory drive shaft
308 is coupled to the fuel control unit 72 at a second end 308b.
[0071] The third accessory drive shaft 310 includes a fifth accessory gear 330 defined about
a first end 310a of the third accessory drive shaft 310. The fifth accessory gear
330 is composed of a suitable metal or metal alloy, and may be cast, machined, forged,
etc. and coupled to the third accessory drive shaft 310. Further, the fifth accessory
gear 330 may be integrally formed with the third accessory drive shaft 310. The fifth
accessory gear 330 comprises a bevel gear that has a plurality of bevel gear teeth
330a. The plurality of bevel gear teeth 330a are defined about a perimeter or circumference
of the fifth accessory gear 330. The plurality of bevel gear teeth 330a are coupled
to and meshingly engage the plurality of bevel gear teeth 174a of the second accessory
gear 174, and the plurality of bevel gear teeth 330a are coupled to and meshingly
engage the plurality of bevel gear teeth 176a of the third accessory gear 176. The
third accessory drive shaft 310 comprises a high speed drive shaft, and is driven
to rotate at about 18,500 rpm. Stated another way, the third accessory drive shaft
310 rotates at a speed, which is about the same as the rotational speed of the shaft
304. Thus, the fifth accessory gear 330 has a diameter, which is different or less
than a diameter of the first accessory gear 172, the second accessory gear 174 and
the third accessory gear 176. The third accessory drive shaft 310 is coupled to the
permanent magnet alternator 70 at a second end 310b.
[0072] The fourth accessory drive shaft 312 includes the third accessory gear 176 defined
about a first end 312a of the fourth accessory drive shaft 312. The plurality of bevel
gear teeth 176a are coupled to and meshingly engage the plurality of bevel gear teeth
330a of the fifth accessory gear 330. The fourth accessory drive shaft 312 comprises
a lower speed drive shaft, and is driven to rotate at about 8,500 rpm. Stated another
way, the fourth accessory drive shaft 312 rotates at a speed, which is different than
the rotational speed of the shaft 304 and is generally less than the rotational speed
of the shaft 304. The fourth accessory drive shaft 312 is coupled to the hydraulic
pump 68 at a second end 312b.
[0073] The fifth accessory drive shaft 314 includes the fourth accessory gear 178 defined
about a first end 314a of the fifth accessory drive shaft 314. The plurality of bevel
gear teeth 178a of the fourth accessory gear 178 are coupled to and meshingly engage
the plurality of bevel gear teeth 324a of the third shaft gear 324. The fifth accessory
drive shaft 314 comprises a high speed drive shaft, and is driven to rotate at about
18,500 rpm. Stated another way, the fifth accessory drive shaft 314 rotates at a speed,
which is about the same as the rotational speed of the shaft 304. A diameter of the
fourth accessory gear 178 is generally about equal to the diameter of the fifth accessory
gear 330; however, it will be understood that the fourth accessory gear 178 can have
a diameter that is different than the diameter of the fifth accessory gear 330. The
fifth accessory drive shaft 314 is coupled to the DC generator 66 at a second end
314b. Generally, the second shaft gear 322 and the fifth accessory gear 330 are substantially
identical, and the first accessory gear 172, the second accessory gear 174, the third
accessory gear 176 are substantially identical.
[0074] Similar to the compact accessory gearbox 60 described with regard to Figs. 1-13,
the gear case 120 is not filled with oil to lubricate the gear train 302. Rather,
oil to lubricate the gear train 302 is provided through the lubrication channel 230
defined through the sleeve 55. In certain examples, oil or lubricating fluid for the
compact accessory gearbox 60 is also received from an oil tank (not shown).
[0075] In order to assemble the shaft 304, in one example, the third shaft gear 324 is slid
over the body 326 to the first end 326a. The spacer 328b is slid over the body 326
until the spacer 328b abuts the third shaft gear 324. The second shaft gear 322 is
slid over the body 326 until the second shaft gear 322 abuts the spacer 328b. The
spacer 328a is slid over the body 326 until the spacer 328a abuts the second shaft
gear 322. The first shaft gear 320 is slid over the body 326 until the first shaft
gear 320 abuts the spacer 328a.
[0076] In one example, in order to assemble the compact accessory gearbox 300, the first
accessory drive shaft 306, the second accessory drive shaft 308, the third accessory
drive shaft 310, the fourth accessory drive shaft 312 and the fifth accessory drive
shaft 314 are each positioned through a respective one of the plurality of apertures
128 defined through the first portion 124 of the gear case 120. Respective ones of
the bearing assemblies 130 are coupled to each of the first accessory drive shaft
306, the second accessory drive shaft 308, the third accessory drive shaft 310, the
fourth accessory drive shaft 312 and the fifth accessory drive shaft 314 and a plurality
of mechanical fasteners are inserted through the coupling bores 140a to couple the
bearing assemblies 130 to the first portion 124, thereby coupling the first accessory
drive shaft 306, the second accessory drive shaft 308, the third accessory drive shaft
310, the fourth accessory drive shaft 312 and the fifth accessory drive shaft 314
to the first portion 124 of the gear case 120.
[0077] With the shaft 304 assembled, the shaft 304 is inserted through the aperture 128"
until the third shaft gear 324 meshingly engages with the fourth accessory gear 178.
The bearing assembly 130 is slid over the second end 326b of the body 326 and a plurality
of mechanical fasteners are inserted into the coupling bores 140a to couple the bearing
assembly 130 to the first portion 124 of the gear case 120. The second portion 126
is positioned over the first portion 124 and coupled to the first portion 124 via
one or more mechanical fasteners. With the first portion 124 and the second portion
126 of the gear case 120 coupled together, the gear case 120 is coupled to the gas
turbine engine 10 as discussed with regard to the compact accessory gearbox 60 of
Figs. 1-13. The compact accessory gearbox 300 has a volume that is about 1/18
th the size of a conventional gearbox, and provides about a 93 percent reduction in
space required within the engine nacelle N for the compact accessory gearbox 300 when
compared to a conventional gearbox.
[0078] In one example, with the high pressure driveshaft 46 driving or rotating the towershaft
54, the torque from the high pressure driveshaft 46 is transmitted through the towershaft
54, the sleeve 55 and into the gear train 302 via the meshing engagement of the gear
58 with the first shaft gear 320. Thus, the rotation of the towershaft 54 rotates
the shaft 304 about the shaft axis of rotation LR2. The rotation of the shaft 304
drives or rotates the first accessory drive shaft 306 (via the engagement between
the second shaft gear 322 and the first accessory gear 172); and drives or rotates
the fifth accessory drive shaft 314 (via the engagement between the third shaft gear
324 and the fourth accessory gear 178). The rotation of the first accessory gear 172
drives or rotates the second accessory gear 174, and thus, the second accessory drive
shaft 308. The rotation of the second accessory gear 174 drives or rotates the fifth
accessory gear 330, and thus, the third accessory drive shaft 310. The rotation of
the fifth accessory gear 330 drives or rotates the third accessory gear 176, and thus,
the fourth accessory drive shaft 312. The rotation of the drive shafts 306-314 provides
input torque the respective accessories 74, 72, 70, 68 and 66 for operating the respective
accessories 74, 72, 70, 68 and 66.
[0079] Prior to a start-up of the gas turbine engine 10, the starter valve 62 may direct
pressurized air to the starter turbine 64. The starter turbine 64 rotates the shaft
304, and the engagement between the first shaft gear 320 and the gear 58 transmits
the torque from the starter turbine 64 to the high pressure driveshaft 46, which causes
the high pressure driveshaft 46 to rotate. The rotation of the high pressure driveshaft
46 drives the compressor 32 and the high pressure turbine 38, thereby enabling a start-up
of the gas turbine engine 10.
[0080] With reference to Fig. 15, a compact accessory system 400 is shown. As the compact
accessory system 400 is similar to the compact accessory system 12 discussed with
regard to Figs. 1-13, only the differences between the compact accessory system 400
and the compact accessory system 12 will be discussed in detail herein, with the same
reference numerals used to denote the same or substantially similar components. The
compact accessory system 12 can be employed with the gas turbine engine 10 to transmit
torque from the towershaft 54 to the accessories 64-74.
[0081] In this example, the compact accessory system 400 includes a compact accessory gearbox
402, which drives various accessories, including, but not limited to, the starter
valve 62, the starter turbine 64, the direct-current (DC) generator 66, the hydraulic
pump 68, the permanent magnet alternator 70, the fuel control unit 72 and the lubrication
pump 74. Generally, the compact accessory gearbox 402 is coupled to the towershaft
54 via the gear 58 to receive the torque from the sleeve 55 and drive the accessories
62-74. It should be noted that the accessories 62-74 described herein are merely exemplary,
as the compact accessory gearbox 60 may be used to drive any suitable accessory associated
with the gas turbine engine 10. One or more of the accessories 64-74 can be coupled
to the compact accessory gearbox 402 via the adaptor 80.
[0082] The compact accessory gearbox 402 includes a housing or gear case 404 and a gear
train 406 (Fig. 16). In this example, the gear case 404 comprises a two-piece housing;
however, the gear case 404 may comprise a one-piece housing, if desired. The gear
case 404 is composed of a metal or metal alloy, which is stamped, machined or forged,
etc. to define the shape of the gear case 404. Generally, the gear case 120 comprises
a plurality of apertures 408 to couple the gear train 406 to the various accessories
64-74. The plurality of apertures 128 are defined about the gear case 404 so as to
extend about a perimeter of the gear case 404, such that the accessories 62-74 are
arranged about a perimeter of the gear case 404. Generally, the accessories 62-74
are arranged substantially circumferentially about the gear case 404, which enables
for a reduction in the volume of the engine nacelle N. In certain instances, one or
more bearing assemblies, such as the bearing assemblies 130, may be coupled between
the accessories 62-74 and the gear case 404 to provided support for the rotation of
the various portions of the gear train 406 relative to the gear case 404.
[0083] With reference to Fig. 16, the gear train 406 is shown without the gear case 404
and the accessories 62-74 for clarity. The gear train 406 includes a shaft 410, a
first accessory drive shaft 412, a second accessory drive shaft 414, a third accessory
drive shaft 416, a fourth accessory drive shaft 418 and a gear set 419. As shown in
Fig. 15, the first accessory drive shaft 412 drives the fuel control unit 72, the
second accessory drive shaft 414 drives the permanent magnet alternator 70, the third
accessory drive shaft 416 drives the lubrication pump 74 and the fourth accessory
drive shaft 418 drives the hydraulic pump 68. The shaft 410 is driven by the starter
turbine 64, and drives the DC generator 66.
[0084] With reference to Fig. 17, the shaft 410 has a shaft axis of rotation LR3, which
is substantially transverse to the axis of rotation TR of the towershaft 54. In one
example, the axis of rotation TR of the towershaft 54 is angularly offset from the
shaft axis of rotation LR3 by an angle δ. The angle δ is about 53 degrees to about
93 degrees. With reference back to Fig. 16, the axis of rotation LR3 of the shaft
410 is substantially parallel to the axis of rotation R of the gas turbine engine
10 (Fig. 1). The first accessory drive shaft 412 has a first accessory axis of rotation
R1b, which is substantially transverse to the axis of rotation LR3 of the shaft 410.
The second accessory drive shaft 414 has a second accessory axis of rotation R2b,
which is substantially transverse to the axis of rotation LR3 of the shaft 410, and
substantially transverse to the first accessory axis of rotation R1b. The third accessory
drive shaft 416 has a third accessory axis of rotation R3b, which is substantially
transverse to the axis of rotation LR3 of the shaft 410, and is substantially parallel
to the first accessory axis of rotation R1b. The third accessory axis of rotation
R3b is also substantially transverse to the second accessory axis of rotation R2b.
The fourth accessory drive shaft 418 has a fourth accessory axis of rotation R4b,
which is substantially transverse to the axis of rotation LR3 of the shaft 410, and
is substantially transverse to the third accessory axis of rotation R3b. The fourth
accessory axis of rotation R4b is substantially transverse to the first accessory
axis of rotation R1b. The fourth accessory axis of rotation R4b is substantially parallel
to the second axis of rotation R2b. Each of the first accessory axis of rotation R1b,
the second accessory axis of rotation R2b, the third accessory axis of rotation R3b
and the fourth accessory axis of rotation R4b define the centerlines for the respective
accessory drive shafts 412-418. The shaft axis of rotation LR3 defines the central
axis for the shaft 410. Further, in this example, the first accessory axis of rotation
R1b, the second accessory axis of rotation R2b, the third accessory axis of rotation
R3b and the fourth accessory axis of rotation R4b intersect at a single point P3 along
the axis of rotation RL3 of the shaft 410.
[0085] The first accessory axis of rotation R1b is spaced apart from the second accessory
axis of rotation R2b by an angle α2. In one example, the angle α2 is about 60 degrees
to about 80 degrees. Similarly, the third accessory axis of rotation R3b is spaced
apart from the fourth accessory axis of rotation R4 by the angle α2. The second accessory
axis of rotation R2b is spaced apart from the shaft axis of rotation LR3 by an angle
β2. In one example, the angle β2 is about 45 degrees to about 65 degrees. Similarly,
the third accessory axis of rotation R3b is spaced apart from the shaft axis of rotation
LR3 by the angle β2. Thus, the accessory drive shafts 412-418 are generally spaced
apart in a substantially circular manner, which results in the placement of the accessories
62-74 substantially circumferentially about the gear case 404, allowing for a reduction
in a space required in the engine nacelle N for the accessories 62-74. One or more
of the accessory axes of rotation R1b-R4b may also be angled relative to the shaft
axis of rotation LR3, if desired. For example, with reference to Fig. 17, the axes
of rotation R1b-R4b may be angled at an angle γ relative to the shaft axis of rotation
LR3. In one example, the angle γ comprises about 15 to about 35 degrees.
[0086] With reference to Fig. 17, the shaft 410 is directly coupled to the towershaft 54,
and comprises a high speed shaft. For example, the shaft 410 rotates at about 18,500
revolutions per minute (rpm). The shaft 410 includes a first shaft gear 420 and a
second shaft gear 422 each arranged on and coupled to a body 424 of the shaft 410.
It should be noted that while the first shaft gear 420 and the second shaft gear 422
are illustrated herein as being integrally formed with the shaft 410, one or more
of the first shaft gear 420 and the second shaft gear 422 may be formed separately
and coupled to the body 424 of the shaft 410. The first shaft gear 420, second shaft
gear 422 and the body 424 are generally formed of a metal or metal alloy, and may
be cast, machined, forged, etc. In this example, the first shaft gear 420 comprises
a bevel gear and the second shaft gear 422 comprises a bevel pinion gear. Each of
the first shaft gear 420 and the second shaft gear 422 have a respective plurality
of bevel gear teeth 420a, 422a (gear teeth are not illustrated in Figs. 16 and 17
for clarity). The plurality of bevel gear teeth 420a, 422a are defined about a perimeter
or circumference of each of the shaft gears 420, 422. The plurality of bevel gear
teeth 420a of the first shaft gear 420 are coupled to and meshingly engage with the
plurality of bevel gear teeth 58a of the gear 58 of the towershaft 54. The plurality
of bevel gear teeth 422a (or plurality of spur gear teeth) of the second shaft gear
422 are coupled to and meshingly engage with a plurality of bevel gear (or spur gear)
teeth 440a of the gear set 419. In one example, the first shaft gear 420 also includes
a projection 420b, which aids in coupling the shaft 410 to the gear case 404, while
setting the correct spacing between the gear case 404 and the rotating shaft 410 and
sleeve 55. It should be noted that while the second shaft gear 422 is described and
illustrated herein as a bevel gear that meshingly engages with the plurality of bevel
gear teeth 440a of a face gear 440 of the gear set 419, in various embodiments, the
second shaft gear 422 can be a spur gear that meshingly engages with a plurality of
spur gear teeth 440a of a face 444 of a face gear 440 of the gear set 419.
[0087] The body 424 of the shaft 410 includes a first end 424a opposite a second end 424b.
Generally, the first shaft gear 420 and the second shaft gear 422 are coupled near
the first end 424a of the body 424. The starter turbine 64 is coupled to the first
end 424a, and the DC generator 66 is coupled to the second end 424b (Fig. 15).
[0088] With reference back to Fig. 16, each of the first accessory drive shaft 412, second
accessory drive shaft 414, third accessory drive shaft 416 and the fourth accessory
drive shaft 418 are composed of a suitable metal or metal alloy, and may be cast,
machined, forged, etc. The first accessory drive shaft 412 includes a first accessory
gear 430 defined about a first end 412a of the first accessory drive shaft 412. The
first accessory gear 430 is composed of a suitable metal or metal alloy, and may be
cast, machined, forged, etc. and coupled to the first accessory drive shaft 412. Further,
the first accessory gear 430 may be integrally formed with the first accessory drive
shaft 412. The first accessory gear 430 comprises a bevel gear that includes a plurality
of bevel gear teeth 430a. The plurality of bevel gear teeth 430a are defined about
a perimeter or circumference of the first accessory gear 430, and the plurality of
bevel gear teeth 430a meshingly engage a plurality of bevel gear teeth 432a of a bevel
gear 432 of the gear set 419. The first accessory drive shaft 412 comprises a lower
speed drive shaft, and is driven to rotate at about 8,500 rpm. Stated another way,
the first accessory drive shaft 412 rotates at a speed, which is different than a
rotational speed of the shaft 410 and is generally less than the rotational speed
of the shaft 410. The first accessory drive shaft 412 is coupled to the fuel control
unit 72 at a second end 412b.
[0089] The second accessory drive shaft 414 includes the second accessory gear 434 defined
about a first end 414a of the second accessory drive shaft 414. The second accessory
gear 434 is composed of a suitable metal or metal alloy, and may be cast, machined,
forged, etc. and coupled to the second accessory drive shaft 414. Further, the second
accessory gear 434 may be integrally formed with the second accessory drive shaft
414. The second accessory gear 434 comprises a bevel gear that includes a plurality
of bevel gear teeth 434a. The plurality of bevel gear teeth 434a are defined about
a perimeter or circumference of the second accessory gear 434, and the plurality of
bevel gear teeth 434a meshingly engages the plurality of bevel gear teeth 432a of
the bevel gear 432. The second accessory drive shaft 414 comprises a lower speed drive
shaft, and is driven to rotate at about 8,500 rpm. Stated another way, the second
accessory drive shaft 414 rotates at a speed, which is different than the rotational
speed of the shaft 410 and is generally about the same as the rotational speed of
the first accessory drive shaft 412. The second accessory drive shaft 414 is coupled
to the permanent magnet alternator 70 at a second end 414b.
[0090] The third accessory drive shaft 416 includes the third accessory gear 436 defined
about a first end 416a of the third accessory drive shaft 416. The third accessory
gear 436 is composed of a suitable metal or metal alloy, and may be cast, machined,
forged, etc. and coupled to the third accessory drive shaft 416. Further, the third
accessory gear 436 may be integrally formed with the third accessory drive shaft 416.
The third accessory gear 436 comprises a bevel gear that includes a plurality of bevel
gear teeth 436a. The plurality of bevel gear teeth 436a are defined about a perimeter
or circumference of the third accessory gear 436, and the plurality of bevel gear
teeth 436a meshingly engages the plurality of bevel gear teeth 432a of the bevel gear
432. The third accessory drive shaft 416 comprises a lower speed drive shaft, and
is driven to rotate at about 8,500 rpm, similar to the second accessory drive shaft
414. The third accessory drive shaft 416 is coupled to the lubrication pump 74 at
a second end 416b.
[0091] The fourth accessory drive shaft 418 includes the fourth accessory gear 438 defined
about a first end 418a of the fourth accessory drive shaft 418. The fourth accessory
gear 438 is composed of a suitable metal or metal alloy, and may be cast, machined,
forged, etc. and coupled to the fourth accessory drive shaft 418. Further, the fourth
accessory gear 438 may be integrally formed with the fourth accessory drive shaft
418. The fourth accessory gear 438 comprises a bevel gear or spur gear that includes
a plurality of bevel gear (or spur gear) teeth 438a. The plurality of bevel gear (or
spur gear) teeth 438a are defined about a perimeter or circumference of the fourth
accessory gear 438, and the plurality of bevel gear (or spur gear) teeth 438a meshingly
engages the plurality of bevel gear (or spur gear) teeth 440a of the face gear 440
of the gear set 419. The fourth accessory drive shaft 418 comprises a high speed drive
shaft, and is driven to rotate at about 18,500 rpm. Stated another way, the fourth
accessory drive shaft 418 rotates at a speed, which is about the same as the rotational
speed of the shaft 410. Thus, the fourth accessory gear 438 has a diameter, which
is different or less than a diameter of the first accessory gear 430, second accessory
gear 434 and third accessory gear 436. The fourth accessory drive shaft 418 is coupled
to the hydraulic pump 68 at a second end 418b.
[0092] The gear set 419 includes the face gear 440 and the bevel gear 432. The face gear
440 can comprise a face gear having spur gear teeth, or can comprise a bevel gear
having bevel gear teeth. Generally, each of the face gear 440 and the bevel gear 432
are annular or ring gears, which are composed of a metal or metal alloy. The face
gear 440 and the bevel gear 432 may be formed using any suitable technique, such as
casting, machining, forging, etc. In this example, the face gear 440 and the bevel
gear 432 are fixedly coupled together for rotation and have a common axis of rotation
FR. With reference to Fig. 17, the bevel gear 432 is coupled to the face gear 440
via one or more mechanical fasteners, such as bolts, screws, etc. which are received
through one or more fastening bores 442 defined through the face gear 440 and defined
partially through the bevel gear 432.
[0093] The face gear 440 is generally coupled outboard of the bevel gear 432, and thus,
the face gear 440 defines an outer circumference for the gear set 419. The face gear
440 includes a face 444. The face 444 is generally defined along the outer circumference
of the face gear 440 and faces the shaft 410. The plurality of bevel gear (or spur
gear) teeth 440a are defined along the face 444, and extend substantially about an
entirety of the face 444. The plurality of bevel gear (or spur gear) teeth 440a are
coupled to or meshingly engage the plurality of bevel gear teeth 422a of the second
shaft gear 422 such that the face gear 440, and thus, the bevel gear 432 are driven
by the shaft 410. The plurality of bevel gear (or spur gear) teeth 440a are also coupled
to or meshingly engage the plurality of bevel gear (or spur gear) teeth 438a of the
fourth accessory gear 438 to drive the fourth accessory drive shaft 418.
[0094] The bevel gear 432 is generally coupled inboard of the face gear 440. The bevel gear
432 includes a second face 446. The second face 446 is generally defined along the
outer circumference of the bevel gear 432 and faces the shaft 410. The plurality of
bevel gear teeth 432a are defined along the second face 446, and extend substantially
about an entirety of the second face 446. With reference Fig. 16, the plurality of
bevel gear teeth 432a are coupled to or meshingly engage the plurality of bevel gear
teeth 430a of the first accessory gear 430, and the plurality of bevel gear teeth
432a are coupled to or meshingly engage the plurality of bevel gear teeth 434a of
the second accessory gear 434. The plurality of bevel gear teeth 432a are also coupled
to or meshingly engage the plurality of bevel gear teeth 436a of the third accessory
gear 436. Thus, the bevel gear 432 drives the first accessory drive shaft 412, the
second accessory drive shaft 414 and the third accessory drive shaft 416.
[0095] Generally, with reference to Fig. 15, the gear case 404 is not filled with oil to
lubricate the gear train 406. In this example, oil to lubricate the gear train 406
is provided through the lubrication channel 230 defined through the towershaft 54.
In certain examples, oil or lubricating fluid for the compact accessory gearbox 402
is also received from an external oil tank (not shown).
[0096] In one example, in order to assemble the compact accessory gearbox 402, the first
accessory drive shaft 412, the second accessory drive shaft 414, the third accessory
drive shaft 416 and the fourth accessory drive shaft 418 are each positioned through
a respective one of the plurality of apertures 408 defined through the gear case 404.
One or more bearing assemblies are coupled to each of the first accessory drive shaft
412, the second accessory drive shaft 414, the third accessory drive shaft 416 and
the fourth accessory drive shaft 418, and are slid over the respective second ends
412b, 414b, 416b, 418b until the bearing assembly is properly positioned. A plurality
of mechanical fasteners may be used to couple the bearing assemblies to the gear case
404, thereby coupling the first accessory drive shaft 412, the second accessory drive
shaft 414, the third accessory drive shaft 416 and the fourth accessory drive shaft
418 to the gear case 404.
[0097] The shaft 410 is inserted through the respective aperture 408 until the fourth shaft
gear 166 contacts a surface of the gear case 404. A bearing assembly may be slid over
the first end 424a of the body 424 (Fig. 17). A plurality of mechanical fasteners
may be used to couple the bearing assembly 130, and thus, the shaft 410 to the gear
case 404. With the face gear 440 coupled to the bevel gear 432 via the fastening bores
442 (Fig. 17), the gear set 419 is positioned such that the face gear 440 is coupled
to the sleeve 55 and the fourth accessory drive shaft 418; and the bevel gear 432
is coupled to the first accessory drive shaft 412, the second accessory drive shaft
414 and the third accessory drive shaft 416. The second portion of the gear case 404
is positioned over the gear set 419 and coupled to the first portion via one or more
mechanical fasteners to enclose the gear case 404. With the gear case 404 assembled,
the gear case 404 is coupled to the gas turbine engine 10 as discussed with regard
to the compact accessory gearbox 60 of Figs. 1-13. The compact accessory gearbox 402
has a volume that is about 1/8
th the size of a conventional gearbox, and provides about an 87 percent reduction in
space required within the engine nacelle N for the compact accessory gearbox 402 when
compared to a conventional gearbox.
[0098] In one example, with the high pressure driveshaft 46 driving or rotating the towershaft
54, the torque from the high pressure driveshaft 46 is transmitted through the towershaft
54 and into the gear train 406 via the meshing engagement of the gear 58 with the
first shaft gear 420. Thus, the rotation of the towershaft 54 rotates the shaft 410
about the shaft axis of rotation LR3. The rotation of the shaft 410 drives or rotates
the face gear 440. The rotation of the face gear 440 drives or rotates the fourth
accessory drive shaft 418 (via the engagement between the face gear 440 and the fourth
accessory gear 438); and drives or rotates the bevel gear 432. The rotation of the
bevel gear 432 drives or rotates the first accessory drive shaft 412 (via the engagement
between the bevel gear 432 and the first accessory gear 430); drives or rotates the
second accessory drive shaft 414 (via the engagement between the bevel gear 432 and
the second accessory gear 434); and drives or rotates the third accessory drive shaft
416 (via the engagement between the bevel gear 432 and the third accessory gear 436).
The rotation of the drive shafts 412-418 provides input torque the respective accessories
72, 70, 74 and 68 for operating the respective accessories 72, 70, 74 and 68. The
rotation of the shaft 410 also provides input torque to the DC generator 66 to operate
the DC generator 66.
[0099] Prior to a start-up of the gas turbine engine 10, the starter valve 62 may direct
pressurized air to the starter turbine 64. The starter turbine 64 rotates the shaft
410, and the engagement between the first shaft gear 420 and the gear 58 transmits
the torque from the starter turbine 64 to the high pressure driveshaft 46, which causes
the high pressure driveshaft 46 to rotate. The rotation of the high pressure driveshaft
46 drives the compressor 32 and the high pressure turbine 38, thereby enabling a start-up
of the gas turbine engine 10.
[0100] It should be noted that the compact accessory gearbox 402 may be configured in various
different ways. For example, with reference to Fig. 18, a simplified view of a gear
train 500 for use with the compact accessory gearbox 402 is shown. As the gear train
500 is similar to the gear train 406 discussed with regard to Figs. 15-17, only the
differences between the gear train 406 and the gear train 500 will be discussed in
detail herein, with the same reference numerals used to denote the same or substantially
similar components. The gear train 500 can be employed with the compact accessory
gearbox 402 in place of the gear train 406 to transmit torque from the towershaft
54 to the accessories 64-74.
[0101] In Figs. 18 and 19, the gear train 500 is shown without the gear case 404 and the
accessories 62-74 for clarity. It should be noted that the shape of the gear case
404 may be modified to accommodate the gear train 500. In this example, the gear train
500 includes the shaft 410, the first accessory drive shaft 412, the second accessory
drive shaft 414, the third accessory drive shaft 416, the fourth accessory drive shaft
418 and a face gear set 502. In the example of Figs. 18 and 19, the face gear set
502 is orientated about 180 degrees relative to the gear set 419 of the gear train
406 discussed with regard to Figs. 15-17.
[0102] With reference to Fig. 19, the face gear set 502 includes the face gear 440 and a
second bevel gear 504. The face gear 440 and the second bevel gear 504 are fixedly
coupled together for rotation and have a common axis of rotation FR. The second bevel
gear 504 is coupled to the face gear 440 via one or more mechanical fasteners, such
as bolts, screws, etc. which are received through one or more fastening bores defined
through the face gear 440 and defined partially through the second bevel gear 504.
[0103] The face gear 440 includes the plurality of bevel gear (or spur gear) teeth 440a
defined along the face 444. The plurality of bevel gear (or spur gear) teeth 440a
are coupled to or meshingly engage the plurality of bevel gear (or spur gear) teeth
422a of the second shaft gear 422 such that the face gear 440, and thus, the second
bevel gear 504 are driven by the shaft 410. The plurality of bevel gear (or spur gear)
teeth 440a are also coupled to or meshingly engage the plurality of bevel gear (or
spur gear) teeth 438a of the fourth accessory gear 438 to drive the fourth accessory
drive shaft 418 (Fig. 18).
[0104] The second bevel gear 504 is generally coupled inboard of the face gear 440, and
is spaced a distance apart from the face gear 440 to provide clearance for the first
accessory gear 430, the second accessory gear 434 and the third accessory gear 436
to interface with a second face 506 of the second bevel gear 504. The second face
506 is generally defined along a perimeter of the second bevel gear 504, such that
the second face 506 faces a portion of the face gear 440. A plurality of bevel gear
teeth 504a are defined along the second face 506, and extend substantially about an
entirety of the second face 506. With reference to Fig. 18, the plurality of bevel
gear teeth 504a are coupled to or meshingly engage the plurality of bevel gear teeth
430a of the first accessory gear 430, and the plurality of bevel gear teeth 504a are
coupled to or meshingly engage the plurality of bevel gear teeth 434a of the second
accessory gear 434. The plurality of bevel gear teeth 504a are also coupled to or
meshingly engage the plurality of bevel gear teeth 436a of the third accessory gear
436. Thus, the second bevel gear 504 drives the first accessory drive shaft 412, the
second accessory drive shaft 414 and the third accessory drive shaft 416.
[0105] In one example, in order to assemble the gear train 500 within the compact accessory
gearbox 402, the first accessory drive shaft 412, the second accessory drive shaft
414, the third accessory drive shaft 416, the fourth accessory drive shaft 418 and
the shaft 410 are coupled to the gear case 404 as discussed with regard to Figs. 15-17,
above. With the face gear 440 coupled to the second bevel gear 504 via the fastening
bores, the face gear set 502 is positioned such that towershaft 54 is coupled to the
shaft 410; the shaft 410 is coupled to the face gear 440; and the face gear 440 is
coupled with the fourth accessory drive shaft 418; and the second bevel gear 504 is
coupled to the first accessory drive shaft 412, the second accessory drive shaft 414
and the third accessory drive shaft 416. The gear case 404 is assembled, and the gear
case 404 is coupled to the gas turbine engine 10 as discussed with regard to the compact
accessory gearbox 60 of Figs. 1-13.
[0106] In this document, relational terms such as first and second, and the like may be
used solely to distinguish one entity or action from another entity or action without
necessarily requiring or implying any actual such relationship or order between such
entities or actions. Numerical ordinals such as "first," "second," "third," etc. simply
denote different singles of a plurality and do not imply any order or sequence unless
specifically defined by the claim language. The sequence of the text in any of the
claims does not imply that process steps must be performed in a temporal or logical
order according to such sequence unless it is specifically defined by the language
of the claim. The process steps may be interchanged in any order without departing
from the scope of the invention as long as such an interchange does not contradict
the claim language and is not logically nonsensical.
[0107] While at least one exemplary embodiment has been presented in the foregoing detailed
description, it should be appreciated that a vast number of variations exist. It should
also be appreciated that the exemplary embodiment or exemplary embodiments are only
examples, and are not intended to limit the scope, applicability, or configuration
of the disclosure in any way. Rather, the foregoing detailed description will provide
those skilled in the art with a convenient road map for implementing the exemplary
embodiment or exemplary embodiments. It should be understood that various changes
can be made in the function and arrangement of elements without departing from the
scope of the disclosure as set forth in the appended claims and the legal equivalents
thereof.
[0108] Embodiments of the present invention are as follows.
- 1. An accessory system for a gas turbine engine having a driveshaft with an axis of
rotation, the accessory system comprising: a towershaft coupled to the driveshaft
and driven by the driveshaft along a towershaft axis of rotation transverse to the
axis of rotation of the gas turbine engine, the towershaft including a towershaft
bevel gear at a distal end; a shaft including a first shaft bevel gear coupled to
the towershaft bevel gear, the shaft rotatable by the towershaft along a shaft axis
of rotation, the shaft axis of rotation transverse to the towershaft axis of rotation
and substantially parallel to the axis of rotation of the gas turbine engine; a first
accessory drive shaft having a first accessory bevel gear driven by the shaft, the
first accessory drive shaft having a first accessory axis of rotation; and a second
accessory drive shaft having a second accessory bevel gear driven by the shaft, the
second accessory drive shaft having a second accessory axis of rotation, each of the
first accessory axis of rotation and the second accessory axis of rotation substantially
transverse to the shaft axis of rotation, and the second accessory axis of rotation
and the first accessory axis of rotation are substantially transverse to each other.
- 2. The accessory system of 1, further comprising: a third accessory drive shaft having
a third accessory bevel gear driven by the shaft, the third accessory drive shaft
having a third accessory axis of rotation, the third accessory axis of rotation substantially
transverse to the shaft axis of rotation and the second accessory axis of rotation,
and the third accessory axis of rotation and the first accessory axis of rotation
are substantially transverse to each other.
- 3. The accessory system of 2, further comprising: a fourth accessory drive shaft having
a fourth accessory bevel gear driven by the shaft, the fourth accessory drive shaft
having a fourth accessory axis of rotation, the fourth accessory axis of rotation
substantially transverse to the shaft axis of rotation and the third accessory axis
of rotation, and the fourth accessory axis of rotation and the second accessory axis
of rotation are substantially transverse to each other.
- 4. The accessory system of 3, wherein the first accessory axis of rotation intersects
the shaft axis of rotation at a first point, the fourth accessory axis of rotation
intersects the shaft axis of rotation at a second point, and the second accessory
axis of rotation and the third accessory axis of rotation intersect the shaft axis
of rotation at a third point, the second point different than the first point.
- 5. The accessory system of 4, wherein the shaft includes a second shaft bevel gear,
a third shaft bevel gear and a fourth shaft bevel gear, with the second shaft bevel
gear coupled to the first accessory bevel gear, the third shaft bevel gear coupled
to the second accessory bevel gear and the fourth shaft bevel gear coupled to the
third accessory bevel gear and the fourth accessory bevel gear.
- 6. The accessory system of 5, further comprising a first spacer coupled to the shaft
between the first shaft bevel gear and the second shaft bevel gear, and a second spacer
coupled to the shaft between the second shaft bevel gear and the third shaft bevel
gear.
- 7. The accessory system of 1, wherein the shaft has a body that defines an air-oil
separator.
- 8. The accessory system of 1, further comprising: a third accessory drive shaft having
a third accessory bevel gear driven by the first accessory bevel gear, the third accessory
drive shaft having a third accessory axis of rotation, the third accessory axis of
rotation substantially transverse to the shaft axis of rotation and the first accessory
axis of rotation, and the third accessory axis of rotation and the second accessory
axis of rotation are substantially transverse to each other.
- 9. The accessory system of 8, further comprising: a fourth accessory drive shaft having
a fourth accessory bevel gear driven by the third accessory bevel gear, the fourth
accessory drive shaft having a fourth accessory axis of rotation substantially parallel
to the shaft axis of rotation; and a fifth accessory drive shaft having a fifth accessory
bevel gear driven by the fourth accessory bevel gear, the fifth accessory drive shaft
having a fifth accessory axis of rotation substantially transverse to the shaft axis
of rotation and substantially transverse to the second accessory axis of rotation.
- 10. The accessory system of 1, further comprising: a face gear set having a face gear
driven by the shaft and a bevel gear driven by the face gear, the first accessory
drive shaft driven by the face gear and the second accessory drive shaft driven by
the bevel gear, wherein the bevel gear includes a face defining a plurality of bevel
gear teeth that faces a portion of the face gear.